Sabira Paper Work

7/31/2019 Sabira Paper Work

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Seminar on:File Handling

SUBMITTED TO:

SUBMMITED BY:

Mr. Chetan Mali

Sabira Hita


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(B.C.A 4th

Sem.)

Files are used to store data in a relatively permanent form, onfloppy disk, hard disk, tape or other form of secondary storage.

Files can hold huge amounts of data if need be. Ordinary variables (even records and arrays) are kept in main

memory which is temporary and rather limited in size.

Difficult to handle large amount of input data.Output would also be lost as soon as we exit

from the program.How do we store data permanently?.

We can use secondary storage device. Data is packaged up on the storage device as data

structures called files.


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Text fileBinary filesSequential filesRandom access files

Text Files:

A text file consists of readable characters separated intolines by newline characters.

(On most PCs, the newline character is actuallyrepresented by the two-character sequence of carriagereturn (ASCII 13), line feed (ASCII 10). (\n)

To insert data into text files:Program file SCR

Abc.txt


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Program for writing into a text file:

Program ABC.txt file contents

#include

int main()

{

ofstream fout;

fout.open("abc.txt");

fout


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Program for reading from a file:

#include

#include#includeint main(){

ifstream fin;char str[80];fin.open("abc.txt");fin>>str; // read only first //string from file

cout


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Binary streamsconsist of data values such as integers,floats or complex data types, using their memoryrepresentation.

Not having to translate numbers into a readable form makes

binary files somewhat more efficient.

Sequential file. With this type of file access one must read thedata in order, much like with a tape, whether the data is reallystored on tape or not.

Random file(or direct access). This type of file access lets you

jump to any location in the file, then to any other, etc., all in areasonable amount of time.

Text Files Binary Files When using a text file,

we write out separatelyeach of the pieces of

data about a givenrecord. The text file will be

readable by an editor

for the text file we willuse the usual output

operator(


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read each of thepieces of record fromthe file separately,using the usual input

operator(>>)

With the binary file

we will use the read

function to read a

whole record,

To access file handling routines:#include

2: To declare variables that can be used to access

file:ifstream in_stream;ofstream out_stream;

3: To connect your program's variable:in_stream.open("infile.txt");out_stream.open("outfile.txt");

4: To see if the file opened successfully:if (in_stream.fail()){ cout


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5: To get data from a file (one option), must declarea variable to hold the data and then read it usingthe extraction operator:

int num;in_stream >> num;

[Compare: cin >> num;]

6: To put data into a file, use insertion operator:out_stream


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I/O in C++:

Different streams are used to represent different kinds ofdata flow.

Each stream is associated with a particular class, whichcontains member functions and definitions for dealing with that particular kind of data

flow.

The following classes in C++ have access to file input and outputfunctions:

ifstream

ofstream fstream


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some other very important member functionMember function

name

Explanation

seekg( ) Used to move reading pointer forward and backward

Syntax

fileobject.seekg( no_of_bytes,mode);Example:

(a) fout.seekg(50,ios::cur); // move 50 bytes forward from current position

(b) fout.seekg(50,ios::beg); // move 50 bytes forward from current beginnin(c) fout.seekg(50,ios::end); // move 50 bytes forward from end .

seekp( ) Used to move writing pointer forward and backward

Syntax

fileobject.seekp(no_of_bytes,mode);Example:

(a) fout.seekp(50,ios::cur); // move 50 bytes forward from current position

(b) fout.seekp(50,ios::beg); // move 50 bytes forward from current beginnin(c) fout.seekp(50,ios::end); // move 50 bytes forward from end .

tellp( ) It return the distance of writing pointer from the beginning in bytesSyntax

Fileobject.tellp( );

Example:

long n = fout.tellp( );

tellg( ) It return the distance of reading pointer from the beginning in bytesSyntax

Fileobject.tellg( );

Example:


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long n = fout.tellg( );

PARAMETER MEANING ios::app Append to end-of file ios::ate goto end of file on opening ios::binary open binary file ios::in Open existing file for reading ios::nocreate open fails if file doesnt exist

ios::noreplace open fails if file already exists ios::out creates new file for writing on ios::trunc Deletes contents if it exists

How to open FileUsing member function Open( ) Using Constructor

Syntax

Filestream object;

Object.open(filename,mode);Example

ifstream fin;

fin.open(abc.txt)

Syntax

Filestream object(filename,mode)

Example

ifstream fin(abc.txt);

NOTE: (a) Mode are optional and given at the end .

(a) Filename must follow the convention of 8.3 and its

extension can be anyone

How to close fileAll types of files can be closed using close( ) member function

Syntax

fileobject.close( );

Example


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fin.close( ); // here fin is an object of istream class

Note: The mode can combine two or more modes using

bit wise or ( | ).


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Example : To read the contents of a text file and display them on the screen.

Program ( using getline member function) Program ( using get( ) member function)#include

#include

#include

int main()

{

char str[100];

ifstream fin;

fin.open("c:\\abc.txt");

while(!fin.eof()){

fin.getline(str,99);

cout


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char name[30];char address[60];};

int main()

{

student s;

ofstream fout;

fout.open("student.dat");

couts.roll;

couts.name;

couts.address;

fout.write((char *)&s,sizeof(student));

fout.close();

return 0;

}

To make class using filehandling


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//***************************************************************// HEADER FILE USED IN PROJECT//****************************************************************

#include#include#include#include#include

//***************************************************************// CLASS USED IN PROJECT//****************************************************************

class account{

int acno;char name[50];int deposit;char type;

public:void create_account(); //function to get data from user


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void show_account(); //function to show data on screenvoid modify(); //function to get new data from uservoid dep(int); //function to accept amount and add to balance amountvoid draw(int); //function to accept amount and subtract from balance amountvoid report(); //function to show data in tabular formatint retacno(); //function to return account numberint retdeposit(); //function to return balance amountchar rettype(); //function to return type of account

}; //class ends here

void account::create_account(){

coutacno;coutdeposit;cout


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}

void account::report(){

cout


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coutch;clrscr();switch(ch){case '1':

write_account();break;

case '2':coutnum;deposit_withdraw(num, 1);break;

case '3':coutnum;deposit_withdraw(num, 2);break;

case '4':coutnum;display_sp(num);break;

case '5':display_all();break;

case '6':coutnum;delete_account(num);break;

case '7':coutnum;modify_account(num);break;

case '8':textattr(128+10);

gotoxy(23,23);

cprintf("\n\n\tThanks for using bank managemnt system");break;

default :cout


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outFile.close();}

//***************************************************************// function to read specific record from file//****************************************************************

void display_sp(int n){

account ac;int flag=0;ifstream inFile;

inFile.open("account.dat",ios::binary);if(!inFile){

cout


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File.seekp(pos,ios::cur);File.write((char *) &ac, sizeof(account));cout


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}cout


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}}

File.close();if(found==0)

cout

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