TOTAL : 45 PERIODS - · PDF fileg payrollprocessing 3.3 13 dynamic memory allocation a...

GE2155 COMPUTER PRACTICE LABORATORY – II L T P C 0 1 2 2

SYLLABUS

1. UNIX COMMANDS 15

Study of Unix OS - Basic Shell Commands - Unix Editor

2. SHELL PROGRAMMING 15

Simple Shell program - Conditional Statements - Testing and Loops

3. C PROGRAMMING ON UNIX 15

Dynamic Storage Allocation-Pointers-Functions-File Handling

TOTAL : 45 PERIODS

TABLE OF CONTENTS

Ex. No Lab # Name of the experiment Page No

1 BASIC UNIX COMMANDS

1.1 1 STUDY OF UNIX OS

UNIX FEATURES

SHELL-KERNEL ARCHITECTURE

FILE SYSTEM

1.2 2 UNIX COMMANDS

GENERAL COMMANDS

DIRECTORY COMMANDS

FILE COMMANDS

1.3 3 VI EDITOR

INSERT MODE

COMMAND MODE

EX MODE

1.4 4 FILTER COMMANDS

HEAD/TAIL

CUT/PASTE

SORT

1.5 5 REGULAR EXPRESSION

GREP

EGREP

2 SHELL PROGRAMMING

2.1 6 SIMPLE SHELL PROGRAMS

A SWAPPING TWO VALUES

B CENTIGRADE TO FAHRENHEIT

C AREA OF A CIRCLE

D SIMPLE INTEREST

2.2 7 DECISION MAKING

A ODD OR EVEN

B BIGGEST OF 3 NUMBERS

C LEAP YEAR


D GRADE DETERMINATION

E EMPLOYEE PAY

F STRING COMPARISON

2.3 8 MULTI-WAY BRANCHING

A VOWEL OR CONSONANT

B SIMPLE CALCULATOR

C RENTAL OPTIONS

D VOTE ELIGIBILITY

2.4 9 LOOPING CONSTRUCTS

A MULTIPLICATION TABLE

B ARMSTRONG NUMBER

C NUMBER REVERSE

D FIBONACCI SERIES

E PRIME NUMBER

F FACTORIAL VALUE

G SUM OF 1+2+3 … + N

H DATA STATISTICS

2.5 10 COMMAND BASED SCRIPTS

A TIME BASED GREET

B MONTH DAYS

C COMMAND MENU

D DIRECTORY LISTING

E FILE TYPE

F FILE DUPLICATES

G DETECT USER LOGON

H COMPILE & EXECUTE

3 C PROGRAMMING

3.1 11 INTRODUCTION TO POINTERS

A REFERENCE & DEREFERENCE

B POINTER VARIABLES

C POINTER TO POINTER

D ADDITION USING POINTERS


E BASIC CALCULATOR

3.2 12 POINTER PROGRAMMING

A PASS BY VALUE / REFERENCE

B RETURN BY REFERENCE

C SUM OF ARRAY ELEMENTS

D PRINTING 2D ARRAY

E STRING COPY

F STUDENT DETAILS

G PAYROLL PROCESSING

3.3 13 DYNAMIC MEMORY ALLOCATION

A MARK AGGREGATE

B STRING REALLOCATION

C 2D ARRAY ALLOCATION

3.4 14 FILE HANDLING

A WRITE TO FILE—CHARACTER I/O

B FILE STATISTICS

C EMPLOYEE FILE—RANDOM ACCESS

3.5 15 COMMAND LINE ARGUMENTS

A ARGUMENT LIST

B FILE COPY—CP

C FILE DISPLAY—CAT

Unix Commands GE2155–Computer Practice II

http://cseannauniv.blogspot.in Vijai Anand

Ex. No: 1.1 STUDY OF UNIX OPERATING SYSTEM

AIM

To introduce the concept of UNIX Operating System

OPERATING SYSTEM

An Operating System is a set of programs that

Functions as an virtual machine by presenting an interface that is easier to programthan the underlying hardware

Acts as resource management through orderly and controlled allocation of theprocessors, memories, and I/O devices among the programs competing for it.

OS TYPES

1. Single User—The system will have its own hard disk, memory, CPU and otherresources all dedicated to a single user. Eg. MS-DOS

2. Multi User—The users having access to a multi-user system will have just a terminaland a keyboard. The other resources such as hard disk, printers are centrally located.The user is expected to simply hook onto his account, perform the work, disconnectand leave quietly. Eg. UNIX

UNIX HISTORY

The spade work for UNIX began at AT&T Bell Laboratories in 1969 by Ken Thompson andDennis Ritchie. The OS was initially known as UNICS (jokingly UNiplexed Information andComputing System). In 1970 UNICS finally became UNIX. In 1973, UNIX was rewritten in1973 in C principally authored by Ritchie.

UNIX FEATURES

1. Multi-user system—Multi-user capability of UNIX allows several users to use thesame computer to perform their tasks. Several terminals [Keyboards and Monitors]are connected to a single powerful computer [UNIX server] and each user can workwith their terminals.

2. Multi-tasking system—Multitasking is the capability of the operating system toperform various task simultaneously, i.e. a user can run multiple tasks concurrently.

3. Programming Facility—UNIX is highly programmable, the UNIX shell has all thenecessary ingredients like conditional and control structures, etc.

4. Security—UNIX allows sharing of data; every user must have a single login nameand password. So, accessing another user’s data is impossible without his permission.

5. Portability—UNIX is portable because it is written in a high level language. So,UNIX can be run on different computers.

http://cseannauniv.blogspot.in



6. Communication—UNIX supports communication between different terminals of thesame server as well as between terminals on different servers.

Apart from these features, UNIX has an extensive Tool kit, exhaustive system calls andLibraries and enhanced GUI (X Window).

ORGANIZATION OF UNIX

The UNIX system is functionally organized at three levels and are:

1. The kernel, which schedules tasks and manages storage;

2. The shell, which connects and interprets users' commands, calls programs frommemory, and executes them; and

3. The tools and applications that offer additional functionality to the OS

UNIX Structure

The kernel is the heart of the system, a collection of programs written in C that directlycommunicate with the hardware. There is only one kernel for any system. It's that part ofUNIX system that is loaded into memory when the system is booted. It manages the systemresources, allocates time between user and processes, decides process priorities, and performsall other tasks. The kernel, in traditional parlance, is often called the Operating system.

The shell, on the other hand, is the "sleeping beauty" of UNIX. It is actually the interfacebetween the user and the kernel. The shell is the agency which takes care of the features ofredirection and has a programming capability of its own.

The Tools and Applications consist of Application Software, Compilers, Database Package,Internet tools, UNIX commands, etc.




FILE SYSTEM

A file in UNIX is nothing but a storehouse of information and everything is treated as a fileby UNIX. The files can be broadly classified as follows:

Ordinary files—Contains stream of data. All data, text, source programs, object andexecutable code, commands fall into this category.

Directory files—Contains no external data. It contains an entry, name of the file andits inode (identification number) for each file and subdirectory under that directory.Directory files are not created by the user but by the UNIX system itself.Device files—Even physical devices are treated as files. These are special in the sensethat any output directed to it will be reflected onto the respective device.

UNIX File System

All files in UNIX are related to one another. The file system of UNIX resembles a tree thatgrows from top to bottom as shown in the figure. The file system begins with a directorycalled root (at the top). The root directory is denoted by a slash (\). Branching from root thereare several directories such as bin, lib, etc, tmp, dev. Each of these directories containsseveral sub-directories and files.

Result

Thus the study of UNIX Operating System has been completed successfully.




Ex. No: 1.2 BASIC COMMANDS

Aim

To study and execute Unix commands.

Unix is security conscious, and can be used only by those persons who have an account.Telnet (Telephone Network) is a Terminal emulator program for TCP/IP networks thatenables users to log on to remote servers.

To logon, type telnet server_ipaddress in run window.User has to authenticate himself by providing username and password. Once verified, agreeting and $ prompt appears. The shell is now ready to receive commands from the user.Options suffixed with a hyphen (–) and arguments are separated by space.

General commands

Command Functiondate Used to display the current system date and time.date +%D Displays date onlydate +%T Displays time onlydate +% Y Displays the year part of datedate +% H Displays the hour part of timecal Calendar of the current monthcal year Displays calendar for all months of the specified yearcal month year Displays calendar for the specified month of the yearwho Login details of all users such as their IP, Terminal No, User name,who am i Used to display the login details of the usertty Used to display the terminal nameuname Displays the Operating Systemuname –r Shows version number of the OS (kernel).uname –n Displays domain name of the serverecho "txt" Displays the given text on the screenecho $HOME Displays the user's home directorybc Basic calculator. Press Ctrl+d to quitlp file Allows the user to spool a job along with others in a print queue.man cmdname Manual for the given command. Press q to exithistory To display the commands used by the user since log on.exit Exit from a process. If shell is the only process then logs out

Directory commands

Command Functionpwd Path of the present working directorymkdir dir A directory is created in the given name under the current directorymkdir dir1 dir2 A number of sub-directories can be created under one strokecd subdir Change Directory. If the subdir starts with / then path starts from

root (absolute) otherwise from current working directory.cd To switch to the home directory.cd / To switch to the root directory.




Command Functioncd .. To move back to the parent directoryrmdir subdir Removes an empty sub-directory.

File commands

Command Functioncat > filename To create a file with some contents. To end typing press Ctrl+d.

The > symbol means redirecting output to a file. (< for input)cat filename Displays the file contents.cat >> filename Used to append contents to a filecp src des Copy files to given location. If already exists, it will be overwrittencp –i src des Warns the user prior to overwriting the destination filecp –r src des Copies the entire directory, all its sub-directories and files.mv old new To rename an existing file or directory. –i option can also be usedmv f1 f2 f3 dir To move a group of files to a directory.mv –v old new Display name of each file as it is moved.rm file Used to delete a file or group of files. –i option can also be usedrm * To delete all the files in the directory.rm –r * Deletes all files and sub-directoriesrm –f * To forcibly remove even write-protected filesls Lists all files and subdirectories (blue colored) in sorted manner.ls name To check whether a file or directory exists.ls name* Short-hand notation to list out filenames of a specific pattern.ls –a Lists all files including hidden files (files beginning with .)ls –x dirname To have specific listing of a directory.ls –R Recursive listing of all files in the subdirectoriesls –l Long listing showing file access rights (read/write/execute-rwx for

user/group/others-ugo).cmp file1 file2 Used to compare two files. Displays nothing if files are identical.wc file It produces a statistics of lines (l), words(w), and characters(c).chmod perm file Changes permission for the specified file. (r=4, w=2, x=1)

chmod 740 file sets all rights for user, read only for groupsand no rights for others

The commands can be combined using the pipeline (|) operator. For example, number ofusers logged in can be obtained as.

who | wc -l

Finally to terminate the unix session execute the command exit or logout.

ResultThus the study and execution of Unix commands has been completed successfully.




[vijai@localhost vijai]$ dateSat Apr 9 13:03:47 IST 2011

[vijai@localhost vijai]$ date +%D04/09/11

[vijai@localhost vijai]$ date +%T13:05:33

[vijai@localhost vijai]$ date +%Y2011

[vijai@localhost vijai]$ date +%H13

[vijai@localhost vijai]$ cal April 2011Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 910 11 12 13 14 15 1617 18 19 20 21 22 2324 25 26 27 28 29 30

[vijai@localhost vijai]$ cal 08 1998 August 1998Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1516 17 18 19 20 21 2223 24 25 26 27 28 2930 31

[vijai@localhost vijai]$ cal 1800 1800

January February MarchSu Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa 1 2 3 4 1 1 5 6 7 8 9 10 11 2 3 4 5 6 7 8 2 3 4 5 6 7 812 13 14 15 16 17 18 9 10 11 12 13 14 15 9 10 11 12 13 14 1519 20 21 22 23 24 25 16 17 18 19 20 21 22 16 17 18 19 20 21 2226 27 28 29 30 31 23 24 25 26 27 28 23 24 25 26 27 28 29 30 31

… … … October November DecemberSu Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa 1 2 3 4 1 1 2 3 4 5 6 5 6 7 8 9 10 11 2 3 4 5 6 7 8 7 8 9 10 11 12 13




12 13 14 15 16 17 18 9 10 11 12 13 14 15 14 15 16 17 18 19 2019 20 21 22 23 24 25 16 17 18 19 20 21 22 21 22 23 24 25 26 2726 27 28 29 30 31 23 24 25 26 27 28 29 28 29 30 31 30

[vijai@localhost vijai]$ whoroot :0 Apr 9 08:41vijai pts/0 Apr 9 13:00 (scl-64)cse1 pts/3 Apr 9 13:18 (scl-41.smkfomra.com)ecea pts/4 Apr 9 13:18 (scl-29.smkfomra.com)

[vijai@localhost vijai]$ who am ivijai pts/0 Apr 9 13:00 (scl-64)

[vijai@localhost vijai]$ tty/dev/pts/0

[vijai@localhost vijai]$ unameLinux

[vijai@localhost vijai]$ uname -r2.4.20-8smp

[vijai@localhost vijai]$ uname -nlocalhost.localdomain

[vijai@localhost vijai]$ echo "How are you"How are you

[vijai@localhost vijai]$ echo $HOME/home/vijai

[vijai@localhost vijai]$ echo $USERvijai

[vijai@localhost vijai]$ bcbc 1.06Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.3+582%32

[vijai@localhost loops]$ pwd/home/vijai/shellscripts/loops

[vijai@localhost vijai]$ mkdir filter[vijai@localhost vijai]$ lsfilter list.sh regexpr shellscripts




[vijai@localhost vijai]$ cd shellscripts/loops/[vijai@localhost loops]$

[vijai@localhost loops]$ cd[vijai@localhost vijai]$

[vijai@localhost loops]$ cd /[vijai@localhost /]$

[vijai@localhost /]$ cd /home/vijai/shellscripts/loops/[vijai@localhost loops]$ cd ..[vijai@localhost shellscripts]$

[vijai@localhost vijai]$ rmdir filter[vijai@localhost vijai]$ lslist.sh regexpr shellscripts

[vijai@localhost vijai]$ cat > greethi ece-awishing u the best[vijai@localhost vijai]$ cat greethi ece-awishing u the best

[vijai@localhost vijai]$ cat >> greetbye[vijai@localhost vijai]$ cat greethi ece-awishing u the bestbye

[vijai@localhost vijai]$ lsgreet list.sh regexpr shellscripts

[vijai@localhost vijai]$ ls -a. .bash_logout .canna .gtkrc regexpr .viminfo.tmp.. .bash_profile .emacs .kde shellscripts .xemacs.bash_history .bashrc greet list.sh .viminfo

[vijai@localhost vijai]$ ls -ltotal 16-rw-rw-r-- 1 vijai vijai 32 Apr 11 14:52 greet-rw-rw-r-- 1 vijai vijai 30 Apr 4 13:58 list.shdrwxrwxr-x 2 vijai vijai 4096 Apr 9 14:30 regexprdrwxrwxr-x 7 vijai vijai 4096 Apr 4 14:57 shellscripts

[vijai@localhost vijai]$ cp greet ./regexpr/[vijai@localhost vijai]$ ls




greet list.sh regexpr shellscripts[vijai@localhost vijai]$ ls ./regexprdemo greet

[vijai@localhost vijai]$ cp -i greet ./regexpr/cp: overwrite 'greet'? n

[vijai@localhost vijai]$ mv greet greet.txt[vijai@localhost vijai]$ lsgreet.txt list.sh regexpr shellscripts

[vijai@localhost vijai]$ mv greet.txt ./regexpr/[vijai@localhost vijai]$ lslist.sh regexpr shellscripts[vijai@localhost vijai]$ ls ./regexpr/demo greet.txt

[vijai@localhost vijai]$ lsfact.sh list.sh prime.sh regexpr shellscripts[vijai@localhost vijai]$ rm -i *.shrm: remove regular file 'fact.sh'? yrm: remove regular file 'list.sh'? nrm: remove regular file 'prime.sh'? y[vijai@localhost vijai]$ lslist.sh regexpr shellscripts

[vijai@localhost vijai]$ wc list.sh 4 9 30 list.sh[vijai@localhost vijai]$ wc -l list.sh 4 list.sh

[vijai@localhost vijai]$ cmp list.sh fact.shlist.sh fact.sh differ: byte 1, line 1

[vijai@localhost vijai]$ ls -l list.sh-rw-rw-r-- 1 vijai vijai 30 Apr 4 13:58 list.sh[vijai@localhost vijai]$ chmod ug+x list.sh[vijai@localhost vijai]$ ls -l list.sh-rwxrwxr-- 1 vijai vijai 30 Apr 4 13:58 list.sh[vijai@localhost vijai]$ chmod 740 list.sh[vijai@localhost vijai]$ ls -l list.sh-rwxr----- 1 vijai vijai 30 Apr 4 13:58 list.sh




Ex. No: 1.3 STUDY OF VI EDITOR

Aim

To introduce the concept of text editing vi editor and the options regarding the controlof the editor.

vi Editor

A text editor is one of the most common and useful tools in all Operating Systems.Unix provides a versatile editor vi, a full-screen editor and owes its origin to Bill Joy. "vi"stands for visual editor. A vi session begins by invoking vi with or without a filename

$vi$vi filename

The user is presented with a full empty screen, each line beginning with a ~. This is vi's wayof indicating non-existent lines. Out of 25 lines on the terminal, 24 can be used to enter text.The last line is reserved for commands and also used by the system to display messages. vifunctions in three modes namely:

1. Input mode—Where any key depressed is entered as text2. Command mode—Where keys are used as commands to act on text (initial mode)3. ex mode—ex mode commands that can be entered in the last line to act on text

vi modes

INPUT MODEvi starts with command mode. To insert text any of the following commands should be used.

Commands Functioni Inserts text to the left of the cursor.I Inserts text at the beginning of line.a Appends text to right of cursorA Appends text at end of lineo Opens line belowO Opens line above

In Input mode the editor displays INSERT in the last line. Press Enter key to start a fresh lineof text in Input mode and the ~ disappears. To quit input mode press Esc key.




COMMAND MODE

EDIT COMMANDS

Command FunctionR Replaces more than a single character. The editor displays REPLACE in

the last line. The existing text is overwritten as they are typed.s Deletes a single character to the left and switches to Input mode.x Deletes the character in the current cursor position?text Locates the text in the file. If not found, the message "Pattern not found"

appears. Use n to repeat the forward search and N for backward search.U or u Reverses the last change made to the buffer.dd Cuts the entire linedw Cuts the entire wordd$ Cuts a line from cursor position to the end of the lined0 Cuts from the cursor position to the start of the lineyy Copies (yanks) the entire lineyw Copies the entire wordp Pastes the text

NAVIGATION COMMANDS

Command Functionb Moves back to beginning of a wordw Moves forward to beginning of word| Moves to start of the line$ Moves to end of the linek Up one linej Down one lineh Left one characterl Right one characterCtrl+f Scrolls a page forwardCtrl+b Scrolls a page backwardlG To move to the specific line

One of the most notable features of vi is the facility of prefixing a number to mostcommands. When prefixed, commands interpret the instruction to be repeated as many times.For example 3x deletes the next three character.

THE EX MODE

The essential save and exit commands form the features of ex mode. Press : (colon) incommand mode to switch to ex mode. The : is displayed in the last line. Type the commandand press Enter key to execute the same.




Command Functionw Saves file, displays the number of lines & characters and returns to

Input mode. If it is an unnamed file then vi puts a message.w file The file is saved under the given nameL1,L2 w file Used to write specific line numbers to some file. The . (dot) represents

current line, 0 for first line and $ could be used to represent last line.q Quits vi session and returns to $ prompt. vi has a safety mechanism

that warns if changes made to file are not saved.q! Quits vi session without saving any changes made since the last savewq Save and exitsh Escape to shell%s/Sstr/Rstr/g This is yet another powerful feature known as substitution. It is

similar to Find and Replace. % represents all lines, g makes it global.To make vi ask for confirmation before replacing use gc instead of g.

r file To insert another file into the current file.new file Splits screen into multiple windows and opens the file.

vi editor

vi Editor

ResultThus the study of text manipulation using vi editor has been completed successfully.

This is vi improved – vimA rudimentary text~~~~~~~~~“Sample.txt” 2L, 30C written




Ex. No: 1.4 Simple Filters

AimTo query a data file using filter commands in unix.

Filters are the central commands of the UNIX tool kit. It acts on data file where lines arerecords, fields delimited by a character not used by the data (mostly |, default is white space).The output is a set of records and the input file is unaltered by these commands.

Command Functionhead used to display the first few records (10 records by default)head stud Displays first 10 records by defaulthead -5 stud Displays first 5 recordshead -1 stud | wc –c length of first recordtail used to display the last few records (10 records by default)tail stud Displays last 10 records by defaulttail -5 stud | tee last5 Last 5 records listed & stored in file last5 using teecut used to extract specific fields. The d option specifies the delimiter and f forspecifying the field list. The c option may be used if extraction is done character wisecut –d \| -f 1,3,4 stud Fields 1,3,4 listedcut –d \| -f 2-4 stud Fields 2,3,4 listedpaste –d \| list1 list2 merges two cut files list1 and list2sort reorders the file as per ASCII sequence. The t option is used to specify delimiter andk option to specify the fieldsort stud Sorted on 1st column by defaultsort –t \| -k 3 stud Sort as per 3rd columnsort –c stud Check if file is sorted using c optionsort -t \| -k 4,4 -k 3,3stud

Sorting on secondary keys

sort -t \| -nr –k 4 stud Sort on numeric field using n option, r for reverseuniq stud Display unique entries in a sorted filetr translates characters. Can be used to change text case. It works with standard input <tr '[a-z]' '[A-Z]' < stud Changes text to upper casenl display file content with lines numbered. The s option is used to specify separatornl –s "|" stud Displays entries numbered with separator |

ResultThus information retrieval using filters has been completed successfully.




stud file

[vijai@localhost filters]$ head stud20057801|Aarthi |ECE |CTS |3600020057702|Albert Jerry |CSE |Wipro |2500020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |1050020057705|Geetha |CSE |Infosys |2300020057806|Irudayaraj |ECE |Polaris |3000020057707|Jaya Prakash |CSE |Ramco |2800020058008|Mahesh |EEE |Microsoft |500020057909|Manimaran |IT |Microsoft |900020058010|Mohammed Mukthar |EEE |Oracle |6000

[vijai@localhost filters]$ head -4 stud20057801|Aarthi |ECE |CTS |3600020057702|Albert Jerry |CSE |Wipro |2500020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |10500

[vijai@localhost filters]$ head -1 stud | wc -c 49

[vijai@localhost filters]$ tail stud20058008|Mahesh |EEE |Microsoft |500020057909|Manimaran |IT |Microsoft |900020058010|Mohammed Mukthar |EEE |Oracle |600020057711|Prithivi Rajan |CSE |Ramco |2500020057712|Pushpak Chander |CSE |CTS |2750020057713|Ramesh |CSE |Wipro |2400020057817|Smitha |ECE |Ramco |3000020057718|Sri Gurumoorthy |IT |Microsoft |11000

20057801|Aarthi |ECE |CTS |3600020057702|Albert Jerry |CSE |Wipro |2500020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |1050020057705|Geetha |CSE |Infosys |2300020057806|Irudayaraj |ECE |Polaris |3000020057707|Jaya Prakash |CSE |Ramco |2800020058008|Mahesh |EEE |Microsoft |500020057909|Manimaran |IT |Microsoft |900020058010|Mohammed Mukthar |EEE |Oracle |600020057711|Prithivi Rajan |CSE |Ramco |2500020057712|Pushpak Chander |CSE |CTS |2750020057713|Ramesh |CSE |Wipro |2400020057817|Smitha |ECE |Ramco |3000020057718|Sri Gurumoorthy |IT |Microsoft |1100020057719|Tamil Selvi |EEE |CTS |350020057720|Thamotharan |IT |CTS |9000




[vijai@localhost filters]$ sort stud20057702|Albert Jerry |CSE |Wipro |2500020057705|Geetha |CSE |Infosys |2300020057707|Jaya Prakash |CSE |Ramco |2800020057711|Prithivi Rajan |CSE |Ramco |2500020057712|Pushpak Chander |CSE |CTS |2750020057713|Ramesh |CSE |Wipro |2400020057718|Sri Gurumoorthy |IT |Microsoft |1100020057719|Tamil Selvi |EEE |CTS |350020057720|Thamotharan |IT |CTS |900020057801|Aarthi |ECE |CTS |3600020057806|Irudayaraj |ECE |Polaris |3000020057817|Smitha |ECE |Ramco |3000020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |1050020057909|Manimaran |IT |Microsoft |900020058008|Mahesh |EEE |Microsoft |500020058010|Mohammed Mukthar |EEE |Oracle |6000

[vijai@localhost filters]$ sort -t \| -k 1 stud20057801|Aarthi |ECE |CTS |3600020057702|Albert Jerry |CSE |Wipro |2500020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |1050020057705|Geetha |CSE |Infosys |2300020057806|Irudayaraj |ECE |Polaris |3000020057707|Jaya Prakash |CSE |Ramco |2800020058008|Mahesh |EEE |Microsoft |500020057909|Manimaran |IT |Microsoft |900020058010|Mohammed Mukthar |EEE |Oracle |600020057711|Prithivi Rajan |CSE |Ramco |2500020057712|Pushpak Chander |CSE |CTS |2750020057713|Ramesh |CSE |Wipro |2400020057817|Smitha |ECE |Ramco |3000020057718|Sri Gurumoorthy |IT |Microsoft |1100020057719|Tamil Selvi |EEE |CTS |350020057720|Thamotharan |IT |CTS |9000

[vijai@localhost filters]$ sort -t \| -k 4,4 -k 3,3 stud20057712|Pushpak Chander |CSE |CTS |2750020057801|Aarthi |ECE |CTS |3600020057719|Tamil Selvi |EEE |CTS |350020057720|Thamotharan |IT |CTS |900020057705|Geetha |CSE |Infosys |2300020058008|Mahesh |EEE |Microsoft |500020057718|Sri Gurumoorthy |IT |Microsoft |1100020057909|Manimaran |IT |Microsoft |900020058010|Mohammed Mukthar |EEE |Oracle |6000




20057806|Irudayaraj |ECE |Polaris |3000020057711|Prithivi Rajan |CSE |Ramco |2500020057707|Jaya Prakash |CSE |Ramco |2800020057817|Smitha |ECE |Ramco |3000020057903|Arun |IT |Ramco |1200020057904|Diwakar |IT |TCS |1050020057713|Ramesh |CSE |Wipro |2400020057702|Albert Jerry |CSE |Wipro |25000

[vijai@localhost filters]$ sort -t \| -nr -k 5 stud20057801|Aarthi |ECE |CTS |3600020057817|Smitha |ECE |Ramco |3000020057806|Irudayaraj |ECE |Polaris |3000020057707|Jaya Prakash |CSE |Ramco |2800020057712|Pushpak Chander |CSE |CTS |2750020057711|Prithivi Rajan |CSE |Ramco |2500020057702|Albert Jerry |CSE |Wipro |2500020057713|Ramesh |CSE |Wipro |2400020057705|Geetha |CSE |Infosys |2300020057903|Arun |IT |Ramco |1200020057718|Sri Gurumoorthy |IT |Microsoft |1100020057904|Diwakar |IT |TCS |1050020057909|Manimaran |IT |Microsoft |900020057720|Thamotharan |IT |CTS |900020058010|Mohammed Mukthar |EEE |Oracle |600020058008|Mahesh |EEE |Microsoft |500020057719|Tamil Selvi |EEE |CTS |3500

[vijai@localhost filters]$ tr '[a-z]' '[A-Z]' < stud20057801|AARTHI |ECE |CTS |3600020057702|ALBERT JERRY |CSE |WIPRO |2500020057903|ARUN |IT |RAMCO |1200020057904|DIWAKAR |IT |TCS |1050020057705|GEETHA |CSE |INFOSYS |2300020057806|IRUDAYARAJ |ECE |POLARIS |3000020057707|JAYA PRAKASH |CSE |RAMCO |2800020058008|MAHESH |EEE |MICROSOFT |500020057909|MANIMARAN |IT |MICROSOFT |900020058010|MOHAMMED MUKTHAR |EEE |ORACLE |600020057711|PRITHIVI RAJAN |CSE |RAMCO |2500020057712|PUSHPAK CHANDER |CSE |CTS |2750020057713|RAMESH |CSE |WIPRO |2400020057817|SMITHA |ECE |RAMCO |3000020057718|SRI GURUMOORTHY |IT |MICROSOFT |1100020057719|TAMIL SELVI |EEE |CTS |350020057720|THAMOTHARAN |IT |CTS |9000




Ex. No: 1.5 Regular Expression

AimTo search for regular expression in a file using grep command in unix.

A frequent requirement is to look for a pattern or expression in a file. Unix handlesthis feature through grep and egrep. grep uses an regular expression to display lines thatmatch and egrep enables searching for multiple patterns. Its usage is

grep options searchtext filename

Command Functiongrep this demo Lists the lines that contains the string thisgrep 'end of' demo Quotes mandatory for text containing spacegrep this demo* Search this in multiple filesgrep –c to demo Number of occurrence of the word to in the filegrep –n sequence demo Display line numbers along with matching linesgrep –v word demo Displays lines that does not contain the text wordgrep –l vim * Displays files containing text vimgrep –i WORD demo Search for text ignoring case differencesgrep '^[0-9]' demo Lines that start with a numbergrep '[0-9]$' demo Lines that end with a numberls -l | grep "^d" Display the subdirectory namesgrep –c "^$" demo Display count of blank lines in the file.grep "2....$" stud Display lines that ends in the range 20000–29999egrep "lower|UPPER" demo Display lines that match either lower or upperegrep "(previous|current)word" demo

Display lines that match either previous word orcurrent word

ResultThus searching text patterns in files using grep has been completed successfully.




demo file

[vijai@localhost regexpr]$ grep this demothis line is the 1st lower case line in this file.Two lines above this line is empty.

[vijai@localhost regexpr]$ grep 'end of' demo1. e - go to the end of the current word.2. E - go to the end of the current WORD.

[vijai@localhost regexpr]$ grep -c to demo5

[vijai@localhost regexpr]$ grep -n sequence demo15:WORD - WORD consists of a sequence of non-blank characters16:Word - word consists of a sequence of letters, digits and underscores.

[vijai@localhost regexpr]$ grep -v word demoTHIS LINE IS THE 1ST UPPER CASE LINE IN THIS FILE.this line is the 1st lower case line in this file.This Line Has All Its First Character Of The Word With Upper Case.

Two lines above this line is empty.vim Word Navigation

2. E - go to the end of the current WORD.4. B - go to the previous WORD.

WORD - WORD consists of a sequence of non-blank characters

telnet 172.16.4.256

THIS LINE IS THE 1ST UPPER CASE LINE IN THIS FILE.this line is the 1st lower case line in this file.This Line Has All Its First Character Of The Word With Upper Case.

Two lines above this line is empty.vim Word Navigation

You may want to do several navigation in relation to words, such as:

1. e - go to the end of the current word.2. E - go to the end of the current WORD.3. b - go to the previous word.4. B - go to the previous WORD.

WORD - WORD consists of a sequence of non-blank charactersWord - word consists of a sequence of letters, digits and underscores.

telnet 172.16.4.256




[vijai@localhost regexpr]$ grep -l vim *demo readme

[vijai@localhost regexpr]$ grep -i WORD demoThis Line Has All Its First Character Of The Word With Upper Case.vim Word NavigationYou may want to do several navigation in relation to words, such as:1. e - go to the end of the current word.2. E - go to the end of the current WORD.3. b - go to the previous word.4. B - go to the previous WORD.WORD - WORD consists of a sequence of non-blank charactersWord - word consists of a sequence of letters, digits and underscores.

[vijai@localhost regexpr]$ grep '^[0-9]' demo1. e - go to the end of the current word.2. E - go to the end of the current WORD.3. b - go to the previous word.4. B - go to the previous WORD.

[vijai@localhost regexpr]$ grep '[0-9]$' demotelnet 172.16.4.256

[vijai@localhost vijai]$ ls -l | grep "^d"drwxrwxr-x 2 vijai vijai 4096 Apr 9 14:30 regexprdrwxrwxr-x 7 vijai vijai 4096 Apr 4 14:57 shellscripts

[vijai@localhost regexpr]$ grep -c "^$" demo5

[vijai@localhost regexpr]$ egrep "lower|UPPER" demoTHIS LINE IS THE 1ST UPPER CASE LINE IN THIS FILE.this line is the 1st lower case line in this file.

[vijai@localhost regexpr]$ egrep "(previous|current) word" demo1. e - go to the end of the current word.3. b - go to the previous word.


Shell Programming GE2155–Computer Practice II


Ex. No: 2.1 SIMPLE PROGRAMS

AimTo write simple shell programs using shell programming fundamentals.

The activities of a shell are not restricted to command interpretation alone. The shell also hasrudimentary programming features. When a group of commands has to be executed regularly,they are stored in a file (with extension .sh). All such files are called shell scripts or shellprograms. Shell programs run in interpretive mode.

The original UNIX came with the Bourne shell (sh) and it is universal even today. Thencame a plethora of shells offering new features. Two of them, C shell (csh) and Korn shell(ksh) has been well accepted by the UNIX fraternity. Linux offers Bash shell (bash) as asuperior alternative to Bourne shell.

Preliminaries

1. Comments in shell script start with #. It can be placed anywhere in a line; the shellignores contents to its right. Comments are recommended but not mandatory

2. Shell variables are loosely typed i.e. not declared. Their type depends on the valueassigned. Variables when used in an expression or output must be prefixed by $.

3. The read statement is shell's internal tool for making scripts interactive.

4. Output is displayed using echo statement. Any text should be within quotes. Escapesequence should be used with –e option.

5. Commands are always enclosed with ` ` (back quotes).

6. Expressions are computed using the expr command. Arithmetic operators are + -* / %. Meta characters * ( ) should be escaped with a \.

7. Multiple statements can be written in a single line separated by ;

8. The shell scripts are executed using the sh command (sh filename).

ResultThus using programming basics, simple shell scripts were executed




2.1.A—Swapping values of two variables

AlgorithmStep 1 : StartStep 2 : Read the values of a and bStep 3 : Interchange the values of a and b using another variable t as follows:

t = aa = bb = t

Step 4 : Print a and bStep 5 : Stop

Program (swap.sh)# Swapping valuesecho -n "Enter value for A : "read aecho -n "Enter value for B : "read bt=$aa=$bb=$techo "Values after Swapping"echo "A Value is $a"echo "B Value is $b"

Output[vijai@localhost simple]$ sh swap.shEnter value for A : 12Enter value for B : 23Values after SwappingA Value is 23B Value is 12

2.1.B—Farenheit to Centigrade Conversion

AlgorithmStep 1 : StartStep 2 : Read fahrenheit valueStep 3 : Convert fahrenheit to centigrade using the formulae: (fahrenheit – 32) × 5/9Step 4 : Print centigradeStep 5 : Stop




Program (degconv.sh)# Degree conversionecho -n "Enter Fahrenheit : "read fc=èxpr $ $f - 32 $ \* 5 / 9ècho "Centigrade is : $c"

Output[vijai@localhost simple]$ sh degconv.shEnter Fahrenheit : 213Centigrade is : 100

2.1.C— Area & Circumference of Circle

Algorithm

Step 1 : StartStep 2 : Define constant pi = 3.14Step 3 : Read the value of radiusStep 4 : Calculate area using formulae: pi × radius2

Step 5 : Calculate circumference using formulae: 2 × pi × radiusStep 6 : Print area and circumferenceStep 7 : Stop

Program (circle.sh)# Circle metrics using readonly variablepi=èxpr "scale=2; 22 / 7" | bc`readonly pi # pi value cannot be alteredecho -n "Enter value for radius : "read radiusarea=èxpr "scale=2; $pi * $radius * $radius" | bc`circum=èxpr "scale=2; 2 * $pi * $radius" | bcècho "Area : $area"echo "Circumference : $circum"

Output[vijai@localhost simple]$ sh circle.shEnter value for radius : 12Area : 452.16Circumference : 75.36




2.1.D— Simple Interest Calculation

AlgorithmStep 1 : StartStep 2 : Read the values principal, rate and yearsStep 3 : Compute simpleinterest using the formulae: (principal × rate × years) / 100Step 4 : Print simpleinterestStep 5 : Stop

Program (simpint.sh)# Interest computation using bcecho -n "Enter Principal amount : "read pecho -n "Enter number of years : "read necho -n "Enter rate of interest : "read rsi=`expr "scale=2; $p * $n *$r / 100" | bc`echo "Simple Interest : $si"

Output[vijai@localhost simple]$ sh simpint.shEnter Principal amount : 1285Enter number of years : 3Enter rate of interest : 5Simple Interest : 192.75




Ex. No: 2.2 CONDITIONAL STATEMENT

AimTo write shell programs using decision-making constructs.

Shell supports decision-making using if statement. The if statement like its counterpart inprogramming languages has the following formats. The first construct executes thestatements when the condition is true. The second construct adds an optional else to thefirst one that has different set of statements to be executed depending on whether thecondition is true or false. The last one is an elif ladder, in which conditions are tested insequence, but only one set of statements is executed.

if [ condition ]then

statementsfi

if [ condition ]then

statementselse

statementsfi

if [condition ]then

statementselif [ condition ]then

statements.. .else

statementsfi

The set of relational and logical operators used in conditional expression is given below. Thenumeric comparison in the shell is confined to integer values only.

Operator Description-eq Equal to-ne Not equal to-gt Greater than-ge Greater than or equal to-lt Less than-le Less than or equal to-a Logical AND-o Logical OR! Logical NOT

ResultThus using if statement scripts with conditional expressions were executed




2.2.A— Odd or even

AlgorithmStep 1 : StartStep 2 : Read numberStep 3 : If number divisible by 2 then

Print "Number is Even"Step 3.1 : else

Print "Number is Odd"Step 4 : Stop

Program (oddeven.sh)# Odd or even using if-elseecho -n "Enter a non-zero number : "read numrem=`expr $num % 2`if [ $rem -eq 0 ]then echo "$num is Even"else echo "$num is Odd"fi

Output[vijai@localhost decision]$ sh oddeven.shEnter a non-zero number : 1212 is Even

2.2.B—Biggest of 3 numbers

AlgorithmStep 1 : StartStep 2 : Read values of a, b and cStep 3 : If a > b and a > c then

Print "A is the biggest"Step 3.1 : else if b > c then

Print "B is the biggest "Step 3.2 : else

Print "C is the biggest"Step 4 : Stop




Program (big3.sh)# Biggest using logical expressionecho -n "Give value for A B and C: "read a b cif [ $a -gt $b -a $a -gt $c ]then echo "A is the Biggest number"elif [ $b -gt $c ]then echo "B is the Biggest number"else echo "C is the Biggest number"fi

Output[vijai@localhost decision]$ sh big3.shGive value for A B and C: 4 3 4C is the Biggest number

2.2.C—Leap year

AlgorithmStep 1 : StartStep 2 : Read the value of yearStep 3 : If year divisible by 400 then

Print "Leap year"Step 3.1 : else if year divisible by 4 and not divisible by 100 then

Print "Leap year"Step 3.2 : else

Print "Not a leap year"Step 4 : Stop

Program (leap.sh)# Leap yearecho -n "Enter a year : "read yearrem1=èxpr $year % 4`rem2=èxpr $year % 100`rem3=èxpr $year % 400ìf [ $rem3 -eq 0 ]then echo "$year is a Leap Year"elif [ $rem2 -ne 0 -a $rem1 -eq 0 ]then echo "$year is a Leap Year"else echo "$year is Not a leap year"fi




Output[vijai@localhost decision]$ sh leap.shEnter a year : 19001900 is Not a leap year

2.2.D—Grade Determination

AlgorithmStep 1 : StartStep 2 : Read markStep 3 : If mark > 90 then

Print "S grade"Step 3.1 : else if mark > 80 then

Print "A grade"Step 3.2 : else if mark > 70 then

Print "B grade"Step 3.3 : else if mark > 60 then

Print "C grade"Step 3.4 : else if mark > 55 then

Print "D grade"Step 3.5 : else if mark 50 then

Print "E grade"Step 3.6 : else

Print "U grade"Step 4 : Stop

Program (grade.sh)echo -n "Enter the mark : "read markif [ $mark -gt 90 ]then echo "S Grade"elif [ $mark -gt 80 ]then echo "A Grade"elif [ $mark -gt 70 ]then echo "B Grade"elif [ $mark -gt 60 ]then echo "C Grade"elif [ $mark -gt 55 ]then echo "D Grade"




elif [ $mark -ge 50 ]then echo "E Grade"else echo "U Grade"fi

Output[vijai@localhost decision]$ sh grade.shEnter the mark : 65C Grade

2.2.E—String comparison

AlgorithmStep 1 : StartStep 2 : Read strings str1 and str2Step 3 : If str1 = str2 then

Print "Strings are the same"Step 3.1 : else

Print "Strings are distinct"Step 4 : Stop

Program (strcomp.sh)echo -n "Enter the first string : "read s1echo -n "Enter the second string : "read s2if [ $s1 == $s2 ]thenecho "Strings are the same"elseecho "Strings are distinct"fi

Output[vijai@localhost decision]$ sh strcomp.shEnter the first string : ece-aEnter the second string : ECE-AStrings are distinct




2.2.F—Employee Pay Calculation

AlgorithmStep 1 : StartStep 2 : Read basicStep 3 : If basic > 30000 then

hra is 5% of basic da is 5% of basic

tax is 10% of basicStep 3.1 : else if basic > 20000 then


tax is 8% of basicStep 3.2 : else


tax is 5% of basicStep 4 : Stop

Program (emppay.sh)echo -n "Enter employee basic pay : "read basicif [ $basic -gt 30000 ]then hra=èxpr 5 \* $basic / 100` da=èxpr 5 \* $basic / 100` tax=èxpr 10 \* $basic / 100èlif [ $basic -gt 20000 ]then hra=èxpr 4 \* $basic / 100` da=èxpr 3 \* $basic / 100` tax=èxpr 8 \* $basic / 100èlse hra=èxpr 3 \* $basic / 100` da=èxpr 2 \* $basic / 100` tax=èxpr 5 \* $basic / 100`figross=èxpr $basic + $da + $hra`netpay=èxpr $gross - $taxècho "Gross Pay : $gross"echo "Net Pay : $netpay"

Output[vijai@localhost decision]$ sh emppay.shEnter employee basic pay : 12000Gross Pay : 12600Net Pay : 12000




Ex. No: 2.3 MULTI-WAY BRANCHING

AimTo write shell programs using case construct to match patterns.

The case statement is used to compare a variables value against a set of constants (integer,character, string, range). If it matches a constant, then the set of statements followed after ) isexecuted till a ;; is encountered. The optional default block is indicated by *. Multipleconstants can be specified in a single pattern separated by |.

case variable inconstant1)

statements ;;constant2)

statements ;;. . .

constantN)statements ;;

*)statements

esac

ResultThus using case statement, shell scripts were executed




2.3.A—Vowel or Consonant

AlgorithmStep 1 : StartStep 2 : Read charStep 3 : If char is either 'a', 'e', 'i', 'o' or 'u' then

Print "It's a vowel"Step 3.1 : else

Print "It's a consonant"Step 4 : Stop

Program (vowel.sh)# Vowel with multiple values in a patternecho -n "Key in a lower case character : "read choicecase $choice in a|e|i|o|u) echo "It's a Vowel";; *) echo "It's a Consonant"esac

Output[vijai@localhost multway]$ sh vowel.cKey in a lower case character : eIt's a Vowel

2.3.B—Simple Calculator

AlgorithmStep 1 : StartStep 2 : Read operands a and bStep 3 : Display operation menuStep 4 : Read optionStep 5 : If option = 1 then

Calculate c = a + bStep 5.1 : else if option = 2 then

Calculate c = a – bStep 5.2 : else if option = 3 then

Calculate c = a * bStep 5.3 : else if option = 4 then

Calculate c = a / bStep 5.4 : else if option = 5 then

Calculate c = a % bStep 5.5 : else

Print "Invalid option"Step 6 : Print cStep 7 : Stop




Program (calc.sh)# Arithmetic operations--multiple statements in a blockecho -n "Enter the two numbers : "read a becho " 1. Addition"echo " 2. Subtraction"echo " 3. Multiplication"echo " 4. Division"echo " 5. Modulo Division"echo -n "Enter the option : "read optioncase $option in 1) c=èxpr $a + $b` echo "$a + $b = $c";; 2) c=èxpr $a - $b` echo "$a - $b = $c";; 3) c=èxpr $a \* $b` echo "$a * $b = $c";; 4) c=èxpr $a / $b` echo "$a / $b = $c";; 5) c=èxpr $a % $b` echo "$a % $b = $c";; *) echo "Invalid Option"esac

Output[vijai@localhost multway]$ sh calc.shEnter the two numbers : 2 4 1. Addition 2. Subtraction 3. Multiplication 4. Division 5. Modulo DivisionEnter the option : 12 + 4 = 6

2.3.C—Rental Options

AlgorithmStep 1 : StartStep 2 : Read vehicleStep 3 : If vehicle = "car" then

Print "Rental is Rs. 20/km"Step 3.1 : else if vehicle = "van" then

Print "Rental is Rs. 10/km"Step 3.2 : else if vehicle = "jeep" then

Print "Rental is Rs. 5/km"Step 3.3 : else if vehicle = "bicycle" then

Print "Rental is Rs. 0.2/km"




Step 3.4 : else Print "Vehicle not available"

Step 4 : Stop

Program (rental.sh)# String matchingecho "Two/Four wheeler rental"echo -n "Enter the required vehicle : "read vehiclecase $vehicle in "car") echo "For $vehicle Rs.20 per km";; "van") echo "For $vehicle Rs.10 per km";; "jeep") echo "For $vehicle Rs.5 per km";; "bicycle") echo "For $vehicle 20 paisa per km";; *) echo "Sorry, I cannot get a $vehicle for you";;esac

Output[vijai@localhost multway]$ sh rental.shTwo/Four wheeler rentalEnter the required vehicle : bicycleFor bicycle 20 paisa per km

2.3.D—Vote Eligibility (vote.sh)

AlgorithmStep 1 : StartStep 2 : Read ageStep 3 : If age 17

Print "Not eligible to vote"Step 3.1 : else

Print "Eligible to vote"Step 4 : Stop

Program# Vote--range matchingecho -n "Enter your age : "read agecase $age in [0-9]|1[0-7])echo "You are not eligible to vote";; *)echo "Eligible to vote"esac

Output[vijai@localhost multway]$ sh vote.shEnter your age : 12You are not eligible to vote




Ex. No: 2.4 LOOPS

AimTo write shell programs using different types of loops.

Shell supports a set of loops such as for, while and until to execute a set of statementsrepeatedly. The body of the loop is contained between do and done statement.

The for loop doesn't test a condition, but uses a list instead.for variable in listdo

statementsdone

The while loop executes the statements as long as the condition remains true.

while [ condition ]do

statementsdone

The until loop complements the while construct in the sense that the statements are executedas long as the condition remains false.

until [ condition ]do

statementsdone

ResultThus using loops, iterative scripts were executed




2.4.A—Multiplication Table

AlgorithmStep 1 : StartStep 2 : Read the value of nStep 3 : Initialize 1 to iStep 4 : Print n, i, n×iStep 5 : Increment i by 1Step 6 : Repeat steps 4 and 5 until i 10Step 7 : Stop

Program (multable.sh)# Multiplication table using for loopclearecho -n "Which multiplication table? : "read nfor x in 1 2 3 4 5 6 7 8 9 10do p=`expr $x \* $n` echo -n "$n X $x = $p" sleep 1done

Output[vijai@localhost loops]$ sh multable.shWhich multiplication table? : 66 X 1 = 66 X 2 = 126 X 3 = 186 X 4 = 246 X 5 = 306 X 6 = 366 X 7 = 426 X 8 = 486 X 9 = 546 X 10= 60

2.4.B—Armstrong Number

AlgorithmStep 1 : StartStep 2 : Read numberStep 3 : Initialize 0 to sum and number to numStep 4 : Extract lastdigit by computing number modulo 10Step 5 : Cube the lastdigit and add it to sumStep 6 : Divide number by 10Step 7: Repeat steps 4–6 until number > 0




Step 8 : If sum = number then Print “Armstrong number”

Step 8.1 : else Print “Not an Armstrong number”

Step 9 : Stop

Program (armstrong.sh)# Armstrong number using while loopecho -n "Enter a number : "read na=$ns=0while [ $n -gt 0 ]do r=èxpr $n % 10` s=èxpr $s + $ $r \* $r \* $r $` n=èxpr $n / 10`doneif [ $a -eq $s ]then echo "Armstrong Number"else echo -n "Not an Armstrong number"fi

Output[vijai@localhost loops]$ sh armstrong.shEnter a number : 370Armstrong Number

2.4.C—Number Reverse

AlgorithmStep 1 : StartStep 2 : Read numberStep 3 : Initialize 0 to reverseStep 4 : Extract lastdigit by computing number modulo 10Step 5 : Compute reverse = reverse10 + lastdigitStep 6 : Divide number by 10Step 7: Repeat steps 4–6 until number > 0Step 8 : Print reverseStep 9 : Stop




Program (reverse.sh)# To reverse a number using while loopecho -n "Enter a number : "read nrd=0while [ $n -gt 0 ]do rem=èxpr $n % 10` rd=èxpr $rd \* 10 + $rem` n=èxpr $n / 10`doneecho "Reversed number is $rd"

Output[vijai@localhost loops]$ sh reverse.shEnter a number : 234Reversed number is 432

2.4.D—Fibonacci Series

AlgorithmStep 1 : StartStep 2 : Read number of terms as nStep 3 : Initialize 0 to f1, 1 to f2 and 2 to iStep 4 : Print initial fibonacci terms f1, f2Step 5 : Generate next term using the formula f3 = f1 + f2Step 6 : Print f3Step 7 : Increment i by 1Step 8 : Assign f2 to f1Step 9 : Assign f3 to f2Step 10 : Repeat steps 5–9 until i nStep 11 : Stop

Program (fibo.sh)# Fibonacci series using while loopecho -n "Enter number of terms : "read necho "Fibonacci Series"f1=0f2=1echo -n "$f1 "echo -n " $f2 "i=2




while [ $i -lt $n ]do f3=èxpr $f1 + $f2` echo -n " $f3 " f1=$f2 f2=$f3 i=èxpr $i + 1`doneecho

Output[vijai@localhost loops]$ sh fibo.shEnter number of terms : 8Fibonacci Series0 1 1 2 3 5 8 13

2.4.E—Prime Number

AlgorithmStep 1 : StartStep 2 : Read the value of nStep 3 : Initialize i to 2Step 4 : If n is divisible by i then

Print “Not Prime” and StopStep 5 : Increment i by 1Step 6 : Repeat steps 4 and 5 until i n/2Step 7 : Print "Prime"Step 8 : Stop

Program (prime.sh)# Prime number using exitecho -n "Enter the number : "read ni=2m=èxpr $n / 2ùntil [ $i -gt $m ]do q=èxpr $n % $i` if [ $q -eq 0 ] then echo "Not a Prime number" exit fi i=èxpr $i + 1`doneecho "Prime number"




Output[vijai@localhost loops]$ sh prime.shEnter the number : 17Prime number

2.4.F—Factorial Value

AlgorithmStep 1 : StartStep 2 : Read numberStep 3 : Initialize 1 to fact and number to iStep 4 : fact = fact * iStep 5 : Decrement i by 1Step 6: Repeat steps 4–6 until i > 0Step 7 : Print factStep 8 : Stop

Program (fact.sh)# Factorial value using untilecho -n "Enter a positive number : "read nf=1until [ $n -lt 1 ]do f=`expr $f \* $n` n=`expr $n - 1`doneecho "Factorial value : $f"

Output[vijai@localhost loops]$ sh fact.shEnter a positive number : 10Factorial value : 3628800

2.4.G—Sum of 1..N natural numbers

AlgorithmStep 1 : StartStep 2 : Read nStep 3 : Initialize 0 to sum and 1 to iStep 4 : Add i to sumStep 5 : Increment i by 1Step 6: Repeat steps 4–6 until i nStep 7 : Print sumStep 8 : Stop




Program (sum1ton.sh)# Sum of 1+2+3+ ... +N numbersecho -n "Enter N value : "read nsum=0i=1until [ $i -gt $n ]do sum=`expr $sum + $i` i=`expr $i + 1`doneecho "The sum of n numbers is $sum"

Output[vijai@localhost loops]$ sh sum1ton.shEnter N value : 26The sum of n numbers is 351

2.4.H—Data Statistics

AlgorithmStep 1 : StartStep 2 : Initialize 0 to pc, sum, iStep 3 : Read a numberStep 4 : If number = 9999 then goto step 10Step 5 : Increment i by 1Step 6 : If number 0 then goto step 3Step 7 : Increment pc by 1Step 8 : Add number to sumStep 9 : Goto step 3Step 10 : Compute avg = sum / pcStep 11 : Print i, pc, avg,Step 12 : Stop

Program (datastat.sh)# Aggregate of positive nos using break and continueclearpc=0s=0i=0




until falsedo echo -n "Enter a number (9999 to quit) : " read n if [ $n -eq 9999 ] then break fi i=èxpr $i + 1` if [ $n -le 0 ] then continue fi pc=èxpr $pc + 1` s=èxpr $s + $n`doneavg=èxpr "scale=2; $s / $pc" | bcècho "Total No. of entries : $i"echo "No. of positive datas : $pc"echo "Positive aggregate : $avg"

Output[vijai@localhost loops]$ sh datastat.shEnter a number (9999 to quit) : 32Enter a number (9999 to quit) : 78Enter a number (9999 to quit) : 0Enter a number (9999 to quit) : 11Enter a number (9999 to quit) : 47Enter a number (9999 to quit) : -9Enter a number (9999 to quit) : 12Enter a number (9999 to quit) : 7Enter a number (9999 to quit) : 9999Total No. of entries : 8No. of positive datas : 6Positive aggregate : 31.16




Ex. No: 2.5 SHELL SCRIPTS

AimTo write shell scripts using shell commands.

The shell's programming features coupled with the UNIX commands make it an extremelyuseful programming language. It is programming practice to tell the system that the filecontents are set of commands to be interpreted by the specified shell in the first line as

#!/bin/bash

File Test operations

The following are some of the options for test expressions that work with files.

Condition Return value-e filename true if file exists-f filename true if file exists and is ordinary-d filename true if file exists and is directory-r filename true if file exists and is readable-w filename true if file exists and is writeable-x filename true if file exists and is executable-s filename true if file exists and is non-emptyfile1 -nt file2 true if file1 is newer than file2

Special Variables

Shell posses certain special variables prefixed by a $ reserved for specific functions. Theseare also known as positional parameters. Some of them are

Variable Description$0 Name of the script$n Command-line arguments ($1 for first, $2 for second argument, and so on)$# Number of arguments supplied to the script$? Exit status of the recent command

ResultThus programming constructs using shell commands were executed




2.5.A—Time based greeting

Program (wish.sh)#!/bin/bashx=`date +%H`mrd=`date +%P`if [ $mrd=='am' ]then if [ $x -le 11 ] then echo "Good Morning" fielse if [ $x -le 2 ] then echo "Good Afternoon" elif [ $x -le 6 ] then echo "Good Evening" else echo "Good Night" fifi

Output[vijai@localhost command]$ sh wish.shGood Morning

2.5.B—Number of days in a month

Program (monthdays.sh)# Number of days in a monthmth=`date +%m`mn=`date +%B`case $mth in 02)echo "February usually has 28 days" echo "If leap year, then it has 29 days" ;; 04|06|09|11)echo "The current month $mn has 30 days" ;; *) echo "The current month $mn has 31 days"esac

Output[vijai@localhost command]$ sh monthdays.shThe current month April has 30 days




2.5.C—Commands menu

Program (cmdmenu.sh)# Menu programch='y'while [ $ch == 'y' ]do echo -e "\tMENU 1. List of files 2. Working Directory 3. Date and Time 4. Users of the system 5. Calendar Enter the option : \c" read choice case "$choice" in 1) ls -l ;; 2) pwd ;; 3) date ;; 4) who ;; 5) cal esac echo -n "Do you wish to continue (y/n) : " read chdone

Output[vijai@localhost command]$ sh cmdmenu.sh MENU 1. List of files 2. Working Directory 3. Date and Time 4. Users of the system 5. Calendar Enter the option : 4vijai pts/20 Apr 4 13:41 (linux-21.smkfomra.com)cse1 pts/13 Apr 4 13:43 (scl-58.smkfomra.com)Do you wish to continue (y/n) : n

2.5.D—Directory Listing

Program (cmdmenu.sh)for x in .do ls -R $xdone




Output[vijai@localhost command]$ sh list.sh.:list.sh shellscripts

./shellscripts:command decision loops patmatch simple

./shellscripts/command:cmdmenu.sh debug.sh dupremove.sh filetype.sh keystroke.sh

./shellscripts/decision:big3.sh emppay.sh grade.sh leap.sh oddeven.sh strcomp.sh

./shellscripts/loops:armstrong.sh datastat.sh fact.sh fibo.sh multable.sh

./shellscripts/patmatch:calc.sh rental.sh vote.sh vowel.sh

./shellscripts/simple:circle.sh degconv.sh simpint.sh swap.sh

2.5.E—Detecting file type

Program (filetype.sh)# File typeecho -n "Enter filename : "read fnameif [ -e $fname ]then if [ -f $fname ] then echo "Regular file" elif [ -d $fname ] then echo "Directory" else echo "Special file" fielse echo "File does not exist"fi

Output[vijai@localhost command]$ sh filetype.shEnter filename : samp.cRegular file




2.5.F—Detecting user when logged on

Program (logdetect.sh)#!/bin/bash#Detect the user at logonwhile truedo if who|grep $1>/dev/null then echo $1 is logged in exit fidone

Output[vijai@localhost command]$ sh logdetect.sh cse1cse1 is logged in

2.5.G—Duplicate file removal

Program (dupremove.sh)# Duplicate file removalif cmp $1 $2then echo "Files $1, $2 are identical" rm $2 echo "$2 file deleted"else echo "Files $1, $2 are distinct"fi

Output[vijai@localhost command]$ sh dupremove.sh samp.c s.cFiles samp.c, s.c are identicals.c file deleted




2.5.H—Compilation and execution of a C program

Program (debug.sh)# Compile and executewhile truedo gcc -o $1.out $1.c case "$?" in 0)echo "Executing ..." ./$1.out exit;; *) sleep 5 vi $1.c esacdone

Output[vijai@localhost command]$ sh debug.sh sampsamp.c:4:10: warning: multi-line string literals aredeprecatedsamp.c:4:10: missing terminating " charactersamp.c:4:10: possible start of unterminated string literalsamp.c: In function `main':samp.c:4: parse error at end of inputExecuting ...Hello

2.5.I—Keystroke detection

Program (keystroke.sh)# Detect key strokeecho "Hit a key and then hit return."read Keypresscase "$Keypress" in [[:lower:]] ) echo "Lowercase letter";; [[:upper:]] ) echo "Uppercase letter";; [0-9] ) echo "Digit";; * ) echo "Punctuation, whitespace, or other";;esac

Output[vijai@localhost command]$ sh keystroke.sh8Digit


C Programming GE2155–Computer Practice II


Ex. No: 3.1 Introduction to Pointers

AimTo learn the concept of pointers in C programs.

Data for a variable is stored at some memory location. Address and Data are two sides anvariable. For instance x = 10 is represented as

Variable Data Address

x 3221216948

The address of a variable can be obtained using & operator known as reference operator. Thevariable's value can be obtained using the dereference operator *.

Pointer Variable

A Pointer variable or a pointer is a special variable that holds the address of another variable.Pointer variable are distinguished from other variables by having an asterik (*) prefixed in thedeclaration statement.

int x, *iptr;

A pointer variable is a derived data type based on either standard, derived or user-defineddata type. A pointer variable can be made to point any variable of its base type by assigningthe variable's address to the pointer. For instance, an integer pointer can point to an integervariable only. A pointer variable is allocated 2 bytes irrespective of the data type it points.

ptr = &x; /* Assigning address X to pointer */

Value of the variable pointed to can be accessed by applying the dereference operator

printf("Value of the variable pointed to %d",*ptr);

A pointer of type void is referred to as generic pointer i.e. it can point to any data type. Sincepointer variables hold address, integers could be added or subtracted to yield another address.A pointer that holds the address of another pointer variable is known as pointer-to-pointer.

ResultThus C programs using pointers were executed.

10




3.1.A—Reference and Dereference operator

Algorithm

Step 1 : StartStep 2 : Initialize x to 10Step 3 : Print the value of xStep 4 : Print the address of x using address operatorStep 5 : Print the value of x by dereferencing the address operatorStep 6 : Stop

Program (refderef.c)/* Data and address */#include <stdio.h>main(){ int x; x=10; printf("Value of x is %d",x); printf("\nAddress of x is %u",&x); printf("\nValue of x is %d\n",*(&x));}

Output[vijai@localhost pointer]$ gcc refderef.c[vijai@localhost pointer]$ ./a.outValue of x is 10Address of x is 3221216948Value of x is 10

3.1.B—Pointer variables

Algorithm

Step 1 : Initialize two integer variables x and y with some values.Step 2 : Create a pointer iptr of integer typeStep 3 : Assign the address of x to iptrStep 4 : Print the value and address stored in iptrStep 5 : Assign the address of y to iptrStep 6 : Print the value and address stored in iptrStep 7 : Print the storage requirement of iptr, address of iptr and main function




Program (ptrvar.c)/* Pointer variables */# include<stdio.h>main(){ int x, y, *iptr; x = 125; iptr = &x ; /* iptr points to x */ y = 23; float *fptr;

printf("X value is %d and stored at %u\n", x, &x); printf("Y value is %d and stored at %u\n", y, &y);

printf("\nInt pointer holds the address %u\n", iptr); printf("Aceesing value thru pointer : %d\n", *iptr);

iptr = &y; /* iptr points to y */ printf("\nInt pointer now holds the address %u\n", iptr); printf("Accessing value thru pointer : %d\n", *iptr);

printf("\nSize of int pointer: %d bytes", sizeof(iptr)); printf("\nSize of float pointer: %d bytes", sizeof(fptr)); printf("\n\nAddress of main function is %u\n", main);}

Output[vijai@localhost pointer]$ gcc ptrvar.c[vijai@localhost pointer]$ ./a.outX value is 125 and stored at 3221216452Y value is 23 and stored at 3221216448

Int pointer holds the address 3221216452Aceesing value thro pointer : 125

Int pointer now holds the address 3221216448Accessing value thro pointer : 23

Size of int pointer: 4 bytesSize of float pointer: 4 bytes

Address of main function is 134513448

3.1.C—Pointer–to–Pointer

Algorithm

Step 1 : Demonstrate void pointer by making it to point to variables of different typeStep 2 : Declare a pointer variable p1 and assign a variable's address of its typeStep 3 : Declare a double pointer p2 and assign it the address of p1Step 4 : Display the address stored in p1, data accessed using p1 and p1's addressStep 5 : Display the address stored in p2, data accessed using p2 and p2's addressStep 6 : Stop




Program (ptrtoptr.c)/* Pointer variables */# include<stdio.h>main(){ int x=12, *p1, **p2; float z=8.5; void *ptr; /* Generic pointer */ ptr = &x ; /* ptr points to x (int) */ ptr = &z; /* ptr points to y (float) */

p1 = &x; p2 = &p1; /* Pointer to pointer */ printf("X value is %d and stored at %u\n", x, &x);

printf("\nPointer holds the address %u\n", p1); printf("Aceesing value thru pointer : %d\n", *p1); printf("Pointer is stored at location : %u\n",&p1);

printf("\nPointer-to-pointer holds the address %u\n", p2); printf("Accessing value thru ptr-to-ptr : %d\n", **p2);

printf("\nSize of ptr-to-ptr: %d bytes\n", sizeof(ptr));}

Output[vijai@localhost pointer]$ gcc ptrtoptr.c[vijai@localhost pointer]$ ./a.outX value is 12 and stored at 3221220804

Pointer holds the address 3221220804Aceesing value thru pointer : 12Pointer is stored at location : 3221220800

Pointer-to-pointer holds the address 3221220800Accessing value thru ptr-to-ptr : 12

Size of ptr-to-ptr: 4 bytes

3.1.D—Addition using pointers

Algorithm

Step 1 : StartStep 2 : Read the values of a and bStep 3 : Assign the address of a and b to x and yStep 4 : Sum the values at locations pointed by x and y and store in cStep 5 : Print cStep 6 : Stop




Program (ptradd.c)/* Addition operations using pointers */#include<stdio.h>main(){ int a,b,c; int *pa,*pb; pa=&a; pb=&b; printf("Enter values for A and B : "); scanf("%d%d",&a,&b); c = *pa + *pb; printf("Sum = %d\n",c);}

Output[vijai@localhost pointer]$ gcc ptradd.c[vijai@localhost pointer]$ ./a.outEnter values for A and B : 4 6Sum = 10

3.1.E—Basic Calculator

Algorithm

Step 1 : StartStep 2 : Read the values of a and bStep 3 : Assign the address of a and b to pointers pa and pbStep 4 : Display a simple calculator menuStep 5 : Based on user choice, perform arithmetic operations using pointer variablesStep 6 : Display the resultStep 7 : Stop

Program (ptrcalc.c)/* Arithmetic operations using pointers */#include<stdio.h>main(){ int a,b,c; int *pa,*pb; char op; pa=&a; pb=&b;

printf("Basic Calculator"); printf("\n + Addition"); printf("\n - Subtraction"); printf("\n * Multiplication"); printf("\n / Quotient");




printf("\n % Remainder"); printf("\n x Quit"); printf("\nEnter operator : "); scanf("%c",&op); printf("Enter two integers : "); scanf("%d%d",&a,&b);

switch (op) { case '+': c = *pa + *pb; break; case '-': c = *pa - *pb; break; case '*': c = *pa * *pb; break; case '/': c = *pa / *pb; break; case '%': c = *pa % *pb; break; default: exit(0); } printf(" %d %c %d = %d\n",a,op,b,c);}

Output[vijai@localhost pointer]$ gcc ptrcalc.c[vijai@localhost pointer]$ ./a.outBasic Calculator + Addition - Subtraction * Multiplication / Quotient % Remainder x QuitEnter operator : +Enter two integers : 12 23 12 + 23 = 35




Ex. No: 3.2 Pointer Programming

AimTo study the advantages of using pointers in C programming.

Pointers & Function

Arguments passed to functions are pass by value i.e., a copy of value of the actual argumentsare passed. Therefore changes made to formal arguments are not reflected to actualarguments. However, to have the actual arguments modified during process by anotherfunction, then addresses of the arguments are passed, instead of values through pointers. Thisis known as pass by reference. Another use of pointers in function is that an address could bereturned, known as return by reference.

Pointers & Arrays

Pointers can be used for efficient traversal of a given array. An array name by itself is apointer to the first element in the array. The address of first element of array X can beexpressed as either &X[0] or X. The i+1th element is termed as &X[i] or X+i. The value of i isreferred to as offset. Thus a pointer can be assigned an array variable and array elements canbe accessed by altering the offset. Similarly for two-dimensional array, Xi+1,j+1 element couldbe accessed as * (* (X + i) + j).

Pointers & Strings

A string variable alternatively can be declared as a character pointer type since string isrepresented as an array of characters. The advantage is that length of the string need not beknown in advance. Strings could be processed using character pointer.

Pointers & Structures

A pointer variable can be assigned a structure as any other type. The members of a structureare accessed using the indirect selection operator (->). Self-referential structure is a structurewhere one of its members is a pointer to the structure itself. Such structures are used toimplement data structures such as list and trees.

ResultThus C programs using pointers were executed and its efficacy realized.




3.2.A—Pass by value & reference

Algorithm

Step 1 : Define function swapval with parameters of type integer that swaps twovariables using a temporary variable.

Step 2 : Define function swapref with parameters of type integer pointer that swaps twovariables using a temporary variable and pointer notation

Step 3 : In main function get values of two variables, say a and bStep 4 : Call function swapval with a and b as arguments (Call by value)Step 5 : Print the values of a and b after function call.Step 6 : Call function swapref with address of a and b as arguments (Call by reference)Step 7 : Print the values of a and b after function call.Step 8 : Stop

Program (passbyref.c)/* Pass by value and reference */#include <stdio.h>main(){ int a, b; void swapval(int, int); /* Pass by reference */ void swapref(int *, int *); /* Pass by value */

printf("Enter the values of A and B : "); scanf("%d%d",&a,&b);

swapval(a,b); /* Call by value */ printf("\nValues after Pass by Value\n"); printf("Value of A is %d\n",a); printf("Value of B is %d\n",b);

swapref(&a, &b); /* Call by reference */ printf("\nValues after Pass by Reference\n"); printf("Value of A is %d\n",a); printf("Value of B is %d\n",b);}

void swapref(int *x, int *y){ int t; t = *x; *x = *y; *y = t;}void swapval(int a, int b){ int t; t = a; a = b; b = t;}




Output[vijai@localhost pointer]$ gcc passbyref.c[vijai@localhost pointer]$ ./a.outEnter the values of A and B : 12 23

Values after Pass by ValueValue of A is 12Value of B is 23

Values after Pass by ReferenceValue of A is 23Value of B is 12

3.2.B—Return by reference

Algorithm

Step 1 : Define function big with parameters of type integer pointer that returns theaddress of the biggest number using pointers (Return by reference)

Step 2 : In main function get values of two variables, say a and bStep 3 : Call function big with address of a and b as arguments (Call by reference)Step 4 : Print value stored at the address returned

Program (retbyref.c)/*Return by reference*/#include <stdio.h>int* big(int* x, int* y){ if (*x > *y) return x; else return y;}

main(){ int a, b; int *p; printf("Enter two values : "); scanf("%d%d",&a,&b); p = big(&a, &b); printf("Biggest is %d\n",*p);}

Output[vijai@localhost pointer]$ gcc retbyref.c[vijai@localhost pointer]$ ./a.outEnter two values : 3 7Biggest is 7




3.2.C—Sum of one-dimensional array

Algorithm

Step 1 : Declare an integer array and an integer pointer p.Step 2 : Get array elements using a for loopStep 3 : Assign starting address of the array to pStep 4 : Set up a loopStep 4.1 : Display the element’s value and address using *p and pStep 4.2 : Add elements value to sumStep 4.3 : Increment p by 1Step 5 : Display sumStep 6 : Stop

Program (array1d.c)/* Pointers and one-dimensional arrays */#include <stdio.h>main(){ int i, n, sum=0; int x[25],*p; printf("Enter number of elements : "); scanf("%d",&n); printf("Enter Array elements : "); for(i=0; i<n; i++) scanf("%d",&x[i]);

p = x; /* p points to array x */ for(i=0; i<n; i++) { printf("x[%d] = %d stored at %u\n",i,*p,p); sum += *p; p++; /* Address incremented points to next element */ } printf("Sum = %d\n ",sum);}

Output[vijai@localhost pointer]$ gcc array1d.c[vijai@localhost pointer]$ ./a.outEnter number of elements : 5Enter Array elements : 12 23 34 45 56x[0] = 12 stored at 3221218368x[1] = 23 stored at 3221218372x[2] = 34 stored at 3221218376x[3] = 45 stored at 3221218380x[4] = 56 stored at 3221218384Sum = 170




3.2.D—Displaying a two-dimensional array

Algorithm

Step 1 : Declare a 2D integer array a with 3 rows and 3 columns and initialize it.Step 2 : Set up a loop with index i that iterates for rows.Step 3 : Set up a loop for the column index j that iterates for columns.Step 4 : Display the element using pointer notation as *(*(a + i) + j))Step 5 : Stop

Program (2darray.c)/* Pointers and 2-dimensional array */#include <stdio.h>main(){ int a[3][3]={{1,2,3}, {4,5,6}, {7,8,9}}; int i,j;

for(i=0; i<3; i++) { for(j=0; j<3; j++) { printf("%4d", *(*(a+i)+j)); } printf("\n"); }}

Output[vijai@localhost pointer]$ gcc 2darray.c[vijai@localhost pointer]$ ./a.out 1 2 3 4 5 6 7 8 9

3.2.E—String copy using pointers

Algorithm

Step 1 : Create function stringcopy with two parameters of type character pointerStep 2 : Set up a loop that iterates until the source string encounters a null characterStep 2.1 : Assign the source string’s character to the destination stringStep 2.2 : Increment the source and destination strings address by 1Step 2.3 : Assign null character to the destination stringStep 3 : In main function, declare two strings src and destStep 4 : Get a string from the user for srcStep 5 : Call stringcopy function and pass the address of src and destStep 6 : Display dest stringStep 7 : Stop




Program (strcopy.c)/* Copy strings using pointers */#include <stdio.h>main(){ void stringcopy(char*, char*); char src[80]; char des[80];

printf("Enter a string : "); gets(src); stringcopy(des, src); printf("Copied string : %s\n", des);}

void stringcopy(char *d, char *s){ while(*s) { *d = *s; s++; d++; } *d = '\0';}

Output[vijai@localhost pointer]$ gcc strcopy.c[vijai@localhost pointer]$ ./a.outEnter a string : Self-conquest is the greatest victoryCopied string : Self-conquest is the greatest victory

3.2.F—Student Detail

Algorithm

Step 1 : Declare a student structure with members rollno, name and markStep 2 : Create a variable s1, and a pointer ptr of type studentStep 3 : Populate s1 with inputs from the userStep 4 : Assign address of s1 to ptrStep 5 : Display the values of structure members using pointer-to-member operatorStep 6 : Stop




Program (studdetail.c)#include<stdio.h>struct student{ long rollno; char name[10]; float mark;};

main(){ struct student *ptr; struct student s1; printf("\nEnter student’s rollno, name, mark : "); scanf("%ld%s%f",&s1.rollno,s1.name,&s1.mark); ptr=&s1; printf("\n\tSTUDENT DETAIL"); printf("\nRollno\tName\t\tMark\n"); printf("%ld\t%s\t%.2f\n",ptr->rollno,ptr->name,ptr->mark);}

Output[vijai@localhost pointer]$ gcc studdetail.c[vijai@localhost pointer]$ ./a.outEnter studentÆs rollno, name, mark : 1032957 Adhithan 10

STUDENT DETAILSRollno Name Mark1032957 Adhithan 10.00

3.2.G—Employee Payroll

Algorithm

Step 1 : Declare a employee structure with members id, name, basic, hra, da, it, grossand netpay

Step 2 : Create array of structure employee as emp and a pointer ptr of type employeeStep 3 : Get number of employees as inputStep 4 : Set up a loop and for each employee obtain values for id, name and basicStep 5 : Set up a loop, and for each employeeStep 5.1 : Compute hra, da, it as given in the problem statementStep 5.2 : Compute gross= hra + daStep 5.3 : Compute netpay = gross - itStep 6 : Display header for employee payrollStep 7 : Assign address of emp to ptrStep 8 : Setup a loop and display employees data in a tabular format using ptrStep 9 : Stop




Program (payroll.c)/* Payroll Generation */#include <stdio.h>struct employee{ int empid; char ename[15]; int basic; float hra; float da; float it; float gross; float netpay;};

main(){ struct employee emp[50], *ptr; int i, j, n; printf("Enter No. of Employees : "); scanf("%d", &n); for(i=0; i<n ;i++) {

printf("\nEnter Employee Details\n");printf("Enter Employee Id : ");scanf("%d", &emp[i].empid);printf("Enter Employee Name : ");scanf("%s", emp[i].ename);printf("Enter Basic Salary : ");scanf("%d", &emp[i].basic);

} ptr=emp; for(i=0; i<n; i++) {

ptr->hra = 0.02 * ptr->basic;ptr->da = 0.01 * ptr->basic;ptr->it = 0.05 * ptr->basic;ptr->gross = ptr->basic+ptr->hra+ptr->da;ptr->netpay = ptr->gross - ptr->it;ptr++;

}




ptr=emp; printf("\n\n\n\t\t\t\tXYZ & Co. Payroll\n\n"); for(i=0;i<80;i++)

printf("*");printf("\nEmpId\tName\t\tBasic\t HRA\t DA\t IT\tGross\t\tNet Pay\n\n");

for(i=0;i<80;i++)printf("*");

for(i=0; i<n; i++) {

printf("\n%d\t%-15s\t%d\t%.2f\t%.2f\t%.2f\t%.2f\t%.2f", ptr->empid,ptr->ename,ptr->basic,ptr->hra,ptr->da,ptr->it,ptr->gross, ptr->netpay);

ptr++; } printf("\n"); for(i=0;i<80;i++)

printf("*");}

Output[vijai@localhost pointer]$ gcc studdetail.c[vijai@localhost pointer]$ ./a.outEnter No. of Employees : 2Enter Employee DetailsEnter Employee Id : 436Enter Employee Name : GopalEnter Basic Salary : 10000Enter Employee DetailsEnter Employee Id : 463Enter Employee Name : RajeshEnter Basic Salary : 22000

XYZ & Co. Payroll

********************************************************************************

EmpId Name Basic HRA DA IT Gross Net Pay

********************************************************************************

436 Gopal 10000 200.00 100.00 500.00 10300.00 9800.00463 Rajesh 22000 440.00 220.00 1100.00 22660.00 21560.00

********************************************************************************




Ex. No: 3.3 Dynamic Memory Allocation

AimTo achieve efficient memory utilization using dynamic memory allocation.

Memory allocated using arrays is insufficient or abundant, thereby inefficient. To overcomethis, memory could be allocated at run-time instead at compile time. The process of allocatingmemory at run time is known as dynamic memory allocation. C inherently does not have thisfacility but supports with memory management functions malloc, calloc and realloc,which can be used to allocate and free memory using free during the program execution.

The memory space located between program and local variable is available known as heapfor dynamic allocation during the execution of the program. The size of heap keeps changingwhen program is executed due to creation and death of variables. Therefore it is possible toencounter memory overflow during dynamic allocation process. In such situations, thememory allocation functions will return a null pointer.

mallocThe malloc function reserves a block of memory of specified size and returns a pointer oftype void containing the first byte of the allocated region. Thus it could be casted to any typeof pointer. The allocated space contains garbage data.

ptr = (cast-type*) malloc(bytesize);

calloccalloc is another memory allocation function that is normally used to request multiple blocksof storage each of the same size and then sets all bytes to zero.

ptr =(casttype*) calloc(blockcount, blocksize);

freeCompile time storage of a variable is allocated and released by the system in accordance withits storage class. With the dynamic runtime allocation, it is our responsibility to release thespace when it is not required, using the free function. The release of storage space becomesimportant when the storage is limited.

free(ptr);

reallocThe memory allocated by using calloc or malloc might be insufficient or excess sometimes.In both the situations the memory size already allocated could be changed with the help offunction realloc. This process is called reallocation of memory.

ptr = realloc(ptr, newsize);

ResultThus memory requirements were allocated dynamically and released later.




3.3.A—Mark aggregate

Algorithm

Step 1 : Read number of students, say nStep 2 : Request memory dynamically to store marks of n students using malloc and store

the address in aStep 3 : If requested block of memory is not allocated then StopStep 4 : Set up a loop and read array elements aiStep 5 : Initialize sum to 0Step 6 : Set up a loop and array elements ai to sumStep 7 : Compute mark aggregate and display itStep 8 : Release the requested memoryStep 9 : Stop

Program (dynalloc.c)/* Dynamic Memory Allocation using malloc() */#include <stdlib.h>#include <malloc.h>#include <stdio.h>main(){ int n, i, *a; float avg, sum=0; printf("Enter the No. of students : "); scanf("%d", &n);

a = (int*) malloc(n * sizeof(int)); if (a == NULL) { printf("\n memory allocations not possible"); exit(-1); } printf("Enter %d marks : ", n); for(i=0; i<n; i++) { scanf("%d",&a[i]); } for(i=0; i<n; i++) sum += a[i]; avg = sum / n; printf("Average mark : %.2f\n",avg); free(a);}

Output[vijai@localhost pointer]$ gcc dynalloc.c[vijai@localhost pointer]$ ./a.outEnter the No. of students : 6Enter 6 marks : 56 67 78 89 90 98Average mark : 79.67




3.3.B—String Reallocation

Algorithm

Step 1 : Declare a string buf and message of type character pointerStep 2 : Obtain text for buf from the userStep 3 : Request memory allocation for message based on length(buf) + 1 using mallocStep 4 : Copy contents of buf to messageStep 5 : Display message and its capacityStep 6 : Obtain another text for buf from the userStep 9 : Request memory reallocation for message based on length(buf) + 1 using reallocStep 11 : Copy contents of buf to messageStep 12 : Display message and its capacityStep 13 : Release the requested memory and Stop

Program (strrealloc.c)/* Dynamic Reallocation for strings */#include <stdio.h>#include <stdlib.h>#include <string.h>main(){ char buf[80], *message;

printf("Enter text and press enter : "); gets(buf); /* Get a string from the user */

/* Allocate the initial block and copy the string to it. */ message = (char*)malloc(strlen(buf)+1); strcpy(message, buf); printf("Content stored is : "); puts(message); /* Display the message. */ printf("Initial allocation : %d bytes\n", strlen(message));

printf("Enter another text and press enter : "); gets(buf); /* Get another string from the user. */

/* Reallocate for the new string */ message = (char *) realloc(message, strlen(buf) + 1); strcpy(message, buf); printf("Modified content is : "); puts(message); /* Display the new message. */ printf("Reallocated memory : %d bytes\n", strlen(message));

free(message);}

Output[vijai@localhost pointer]$ gcc strrealloc.c[vijai@localhost pointer]$ ./a.outEnter text and press enter : Hi!




Content stored is : Hi!Initial allocation : 4 bytesEnter another text and press enter : How r u?Modified content is : How r u?Reallocated memory : 8 bytes

3.3.C—Allocation for two dimensional array

Algorithm

Step 1 : Declare a pointer-to-pointer ptr variableStep 2 : Get number of rows and colsStep 3 : Request memory for ptr based on rows using calloc (Array of pointers)Step 4 : Set up a loop that iterates based on rowsStep 4.1 : Request memory for each array element of ptr based on cols using callocStep 5 : Set up a nested loop and display the 2D array with default valuesStep 6 : Release the requested memory and Stop

Program (2dcalloc.c)/* Dynamic allocation for 2D array */#include <stdio.h>#include <malloc.h>

main(){ int i, j, row, col, **ptr; printf("Enter row and column dimension : "); scanf("%d%d",&row,&col);

/* 2d array is an array of pointers */ ptr = (int *) calloc(row, sizeof(int)); for(i=0; i<row; i++) ptr[i] = (int *) calloc(col, sizeof(int));

/* Display default value 0 assigned due to calloc */ for (i=0; i<row; i++) { for (j=0; j<col; j++) printf("%4d",ptr[i][j]); printf("\n"); } free(ptr);}

Output[vijai@localhost pointer]$ gcc 2dcalloc.c[vijai@localhost pointer]$ ./a.outEnter row and column dimension : 3 4 0 0 0 0 0 0 0 0 0 0 0 0




Ex. No: 3.4 File Handling

AimTo perform disk I/O using file handling

Many application require information stored on auxillary storage device. Suchinformation is stored permanently as a data file that allows to access and alter the informationwhenever necessary.

Opening a File

Prior to performing any activity of a file, the file should be opened. By opening a file, linkbetween the program and the operating system is established. This link exists by means of astructure named FILE, in header file stdio.h. Therefore, it is mandatory for programspertaining to file should include <stdio.h>.

When a request is made for a file to be opened, the operating system returns a pointerto the structure FILE. The pointer is declared as

FILE *fileptr;

A file is opened using the standard function fopen(). The file to be opened is searchedin the disk. If a file could not be opened, a NULL is returned.

fileptr = fopen("filename", "mode");

The file mode specifies the purpose of opening a file. Some of them are

Mode Descriptionr Open an existing file for reading onlyw Open a new file for writing only. If the file exists, its contents are destroyeda Open an existing file for appending. If the file doesn't exist, a new file is created

The I/O operation is done using any of the following functions.

getc & putc

The getc function is used to read a character from the file opened in read mode and assigns itto a character variable. The getc will return an EOF marker when the end-of-file is reached.Thereafter reading is not possible. The putc function writes the character contained in thevariable onto a file opened in write mode. The file pointer moves by one character positionfor every character I/O operation.

charvar = getc(fileptr);putc(charvar, fileptr);

fgets & fputs

Rather than single characters, to deal with strings fgets and fputs are used in a similar manner.




fscanf & fprintf

These functions handle mixed data. Care should be taken that the same format specificationsis used for both read and write operation.

fwrite & fread

Applications might perform I/O as blocks of data, where each block is a fixed number ofcontiguous bytes. A block is generally represented as a structure. The library functions freadand fwrite are intended to be used in situations of this type and requires arguments namelyaddress, size and number of the data block. fread reads a block of data and assigns to astructure variable. fwrite writes contents of a structure variable onto the file.

fread(&structvar, sizeof(structvar), 1, fileptr);fwrite(&structvar, sizeof(structvar), 1, fileptr);

Random Access

In random access any specified part of the file is pointed without the mundane readingthrough the file upto that point. This is achieved with the help of functions fseek, ftell andrewind available in the I/O library.

Function Descriptionftell Returns the number of bytes read or writtenrewind Resets the file pointer to start of the filefseek Moves the file pointer to the desired byte

fseek(fileptr, offset, position);position can take values 0, 1 or 2 indicating begining, current position, and endof the file respectively

Fclose

A file should be closed when all operation on it have been completed. This ensures allinformation associated with the file is flushed out of the buffers and all links to the filebroken. A file must be closed if the same should be opened in a different mode.

fclose(fileptr);

ResultThus sequential and random disk I/O is executed using file handling functions.




3.4.A—Write to a file character-by-character

Algorithm

Step 1 : Declare a file pointer fpStep 2 : Open file CharFile.txt in write mode using fpStep 3 : If file could not be created then StopStep 4 : Read a character from the consoleStep 5 : If character is not end-of-file then write it onto file using putcStep 6 : Repeat steps 4 and 5 until end-of-file is encounteredStep 7 : Close the fileStep 8 : Stop

Program (chario.c)/* File I/O using getc and putc functions */#include <stdio.h>#include <stdlib.h>main(){ FILE *fp; char c;

fp=fopen("CharFile.txt", "w"); if (fp == NULL) { printf("File not Accessible"); exit(-1); }

printf("Input Text--Ctrl + D to Terminate\n"); /* Get data (char by char) from user and write onto file*/ while( (c=getchar()) != EOF) putc(c, fp); fclose(fp);

}

Output[vijai@localhost files]$ gcc chario.c[vijai@localhost files]$ ./a.outInput Text--Ctrl + D to TerminateWelcome to File handlingA file should be opened before an I/OI/O should not conflict with the modeAfter I/O files should be closed[vijai@localhost files]$ cat CharFile.txtWelcome to File handlingA file should be opened before an I/OI/O should not conflict with the modeAfter I/O files should be closed




3.4.B—File Statistics

Algorithm

Step 1 : Declare a file pointer fp and static variables lc, wc, ccStep 2 : Open file CharFile.txt in read mode using fpStep 3 : Fetch a character from the fileStep 4 : Display the character and increment cc by 1Step 5 : If character is a newline then increment lc and wc by 1Step 6 : If character is a whitespace then increment wc by 1Step 7 : Repeat steps 3–6 until end-of-file is encounteredStep 8 : Display number of words, lines and characters in the fileStep 9 : Close the file and Stop

Program (filestat.c)/* Statistics of file-word, lines, character */#include <stdio.h>main(){ FILE *fp; char c; static int lc, wc, cc;

/* File Read and process */ fp=fopen("CharFile.txt", "r"); while( (c=getc(fp)) != EOF ) /* Process char-by-char */ { switch(c) /* Count lines, words & character */ { case '\n' : ++lc; ++wc; break; case ' ' : ++wc; break; default : ++cc; } } printf("No. of lines : %d", lc); printf("\nNo. of words : %d", wc); printf("\nNo. of characters (spaces excl.) : %d\n", cc); fclose(fp);}

Output[vijai@localhost files]$ gcc filestat.c[vijai@localhost files]$ ./a.outNo. of lines : 4




No. of words : 25No. of characters (spaces excl.) : 109

3.4.C—Employee Record

Algorithm

Step 1 : Declare structure employee with members code, name, design and basicStep 2 : Declare a file pointer fp and variables casual of type employeeStep 3 : Open file emp.dat in write mode using fpStep 4 : Set up a loop to input employee data until name='xxx'Step 4.1 : Get full details of an employee using casual with code auto-generatedStep 4.2 : Write casual onto file emp.dat using fwriteStep 5 : Display size of the file using ftell and close itStep 6 : Reopen file emp.dat in read mode using fpStep 7 : Get the employee code for which details are sought.Step 8 : Go to the start of the required data using fseekStep 9 : Load the employee details onto casual using fread and display itStep 10 : Close the file and Stop

Program (emprec.c)/* Binary I/O using fwrite and random fread */#include <stdio.h>#include <string.h>

struct employee{ int code; char name[20]; char desig[20]; float basic;};

main(){ struct employee casual, temp; FILE *fp; int id, eno,n,pos, lb; id = 1000;

fp = fopen("Emp.dat", "w"); printf("\tEnter employee details\n"); while (1) { casual.code=id++; printf("Employee Id : %d", casual.code); printf("\nEnter Name (xxx to quit) : "); scanf("%s", casual.name); if (strcmp(casual.name,"xxx") == 0) break; printf("Enter Designation : ");




scanf("%s", casual.desig); printf("Enter Basic Salary: "); scanf("%f", &casual.basic); fwrite (&casual, sizeof(casual), 1, fp); } n = ftell(fp); printf("\nFile size : %d bytes\n",n); fclose(fp);

/* Record seek */ fp = fopen("Emp.dat", "r"); printf("\nEnter Employee id : "); scanf("%d",&eno); pos = (eno-1000)*sizeof(casual); if (pos < n) { fseek(fp,pos,0); fread (&temp, sizeof(temp), 1, fp); printf("Employee Name : %s\n", temp.name); printf("Employee Designation : %s\n", temp.desig); printf("Employee Basic : %.2f\n", temp.basic); } else printf("\nIncorrect Employee Id"); fclose(fp);}

Output Enter employee detailsEmployee Id : 1000Enter Name (xxx to quit) : PrabakharEnter Designation : AnalystEnter Basic Salary: 34000Employee Id : 1001Enter Name (xxx to quit) : RaghuEnter Designation : AdministratorEnter Basic Salary: 28000Employee Id : 1002Enter Name (xxx to quit) : GokulEnter Designation : ProgrammerEnter Basic Salary: 25000Enter Name (xxx to quit) : xxx

File size : 150 bytes

Enter Employee id : 1001Employee Name : RaghuEmployee Designation : AdministratorEmployee Basic : 28000.00




Ex. No: 3.5 Command Line Arguments

AimTo study the use of command line arguments

Command-line arguments are given after the name of a program in command-line operatingsystems like DOS or Linux, and are passed in to the program from the operating system.

In C, main function can accept two arguments: one argument is number of command linearguments, and the other argument is a list of all of the command line arguments.

main(int argc, char *argv[])

The first one integer, (conventionally called argc) is the argument count. It is the number ofarguments passed into the program from the command line, including the name of theprogram.

The second is a pointer to an array of character strings (conventionally called argv), forargument vector that contains the arguments, one per string. argv[0] is the name of theprogram. After that, every element number less than argc is a command line argument.argv[argc] is a null pointer.

C's model of command line arguments adheres to the following:

Arguments are delimited by white space, which is either a space or a tab.A string surrounded by double quotation marks is interpreted as a single argument.A double quotation mark preceded by a backslash, \", is interpreted as ".Two back slashe (\\) is replaced by a single backslash (\).

For instance, the following command line is interpreted as$./copy cnotes cpnotes

argc = 3 argv[0] = ./copy argv[1] = cnotes argv[2] = cpnotes

Command line arguments are typically used to pass the name of a data file to an application.Programs containing command line parameters are generally used to imitate OS commands.

ResultThus arguments were passed to programs at command line and executed




3.5.A—Listing command line arguments

Program (cmdline.c)/* Command line arguments */#include <stdio.h>main(int argc, int *argv[]){ int i; printf("Number of arguments : %d\n", argc); for(i=0; i<argc; i++) printf("Argument [%d] = %s\n",i, argv[i]);}

Output[vijai@localhost files]$ gcc cmdline.c -o cmdline[vijai@localhost files]$ ./cmdline "C:\\Program Files\\Adobe" readme.txt

Number of arguments : 3Argument [0] = ./cmdlineArgument [1] = C:\Program Files\AdobeArgument [2] = readme.txt

3.5.B—File copy

Program (filecopy.c)/* File copy—imitating cp command */#include <stdio.h>#include <stdlib.h>main(int argc, char *argv[]) /* Command line arguments */{ FILE *src, *des; char ch;

if (argc != 3) { printf("Arguments insufficient\n"); printf("Usage : ./filecopy source dest\n"); exit(-1); } src = fopen(argv[1], "r"); if( src==NULL ) { printf("Source File not Acccessible\n"); exit(-1); }




des = fopen(argv[2], "w"); if(des==NULL) { printf("Unable to create Destination file\n"); exit(-1); }

while (1) { ch=getc(src); if(ch==EOF) break; else putc(ch, des); } printf("File Copied\n"); fclose(src); fclose(des);}

Output[vijai@localhost files]$ gcc filecopy.c -o filecopy[vijai@localhost files]$ ./filecopy Random.txtArguments insufficientUsage : ./filecopy source dest[vijai@localhost files]$ ./filecopy Random.txt r.txtFile Copied[vijai@localhost files]$ lsa.out chario.c cmdline.c emprec.c filecopy.c random.c r.txtCharFile.txt cmdline Employee.txt filecopy filestat.c Random.txt[vijai@localhost files]$ cmp Random.txt r.txt[vijai@localhost files]$

3.5.C—Display file contents

Program (filecat.c)/* Cat command */#include <stdio.h>main(int argc, char *argv[]){ FILE *fp; char c;

if(argc != 2) { fprintf(stderr, "Insufficient arguments\n"); fprintf(stderr, "Usage: ./filecat filename\n"); exit(-1); }




fp = fopen(argv[1], "r"); if(fp == NULL) { fprintf(stderr, "cat: can't open %s\n", argv[1]); exit(-1); }

while((c = getc(fp)) != EOF) putchar(c);

fclose(fp);}

Output[vijai@localhost files]$ gcc filecat.c -o filecat[vijai@localhost files]$ ./filecatInsufficient argumentsUsage: ./filecat filename[vijai@localhost files]$ ./filecat charfile.txtcat: can't open charfile.txt[vijai@localhost files]$ ./filecat CharFile.txtWelcome to File handlingA file should be opened before an I/OI/O should not conflict with the modeAfter I/O files should be closed


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