Differences Between C and Java

8/10/2019 Differences Between C and Java

1/24

Differences between Java

and C

CS-2303, C-Term 2010 1

Differences between Java and C

CS-2303, System Programming Concepts

(Slides include materials from The C Programming Language, 2ndedition, by Kernighan and Ritchie and

from C: How to Program, 5thand 6theditions, by Deitel and Deitel)


2/24


and C

CS-2303, C-Term 2010 2

Java and C

Java is derived from C

Many of its syntactic characteristics are

similar to C

However, there are some huge differences


3/24


and C

CS-2303, C-Term 2010 3

Expressions

Arithmetic operators are the same:

+, , *, /, %, ++,

Numerical type conversion is mostly thesame

Java spells out divide by zero,NaN(not anumber, etc.)

C & C++ are machine dependent

Check the textbooks for details


4/24


and C

CS-2303, C-Term 2010 4

Relational Operators

Relational operators work the same way but return

different results:

>, >=,


5/24


and C

CS-2303, C-Term 2010 5

Conditional and Bitwise Operators

Conditional execution operators are same in Java

and C/C++:

||, &&, ? followed by:

Bitwise operators are same in Java and C/C++:

|, &, ^ for bit-by-bit operations with a word

Shift operators differ a little bit

> (right shift)is machine dependent in C/C++

I.e., whether to fill from left with zeros or sign bits


6/24


and C

CS-2303, C-Term 2010 6

Assignment and Unary Operators

Assignment operators work the same:

=, +=, -=, *=, /=, &=, |=, ^=

The following unary operators are availableC/C++ but not in Java

~ invert the bits of a word

* pointer dereference

& pointer creation

(type) cast (i.e., forceable type conversion)

sizeof # of bytes in operand or data type

-> pointer dereference with field selection


7/24


and C

CS-2303, C-Term 2010 7

Summary about Expressions and Operators

Pretty much the same in C/C++ and Java

Be sure to check details in textbook

Be sure to check operator precedence Table 2-1 in K&R

Distributed throughout text in D&D


8/24


and C

CS-2303, C-Term 2010 8

Statements

Statements in C/C++: Labeled statement

Expression statement

Compound statement Selection statement

Iteration statement

Jump statement


9/24


and C

CS-2303, C-Term 2010 9

Statements




Iteration statement

Jump statement

E.g., cases of a switch

statement

Similar to Java


10/24


and C

CS-2303, C-Term 2010 10

Statements




Iteration statement

Jump statement

Any expressionfollowed by ';'

Much like to Java


11/24


and C

CS-2303, C-Term 2010 11

Statements




Iteration statement

Jump statement

Sequence of statementsenclosed in "{}"

Called a block in Java


12/24


and C

CS-2303, C-Term 2010 12

Statements




Iteration statement

Jump statement

switch (expr)if (expr)statement

if (expr) statement

else statement

Same as in Java


13/24


and C

CS-2303, C-Term 2010 13

Statements




Iteration statement

Jump statement

while (expr) statement

do statement while (exp

for (exp1; exp2, exp3)

statementVery similar to Java


14/24


and C

CS-2303, C-Term 2010 14

Statements




Iteration statement

Jump statementbreak;

continue;

return expr

Very similar to Java

goto

Not present in Java

Not allowed in thiscourse


15/24


and C

CS-2303, C-Term 2010 15

Summary about Statements

Pretty much the same in C/C++ and Java

Be sure to check details in textbooks


16/24


and C

CS-2303, C-Term 2010 16

Formatted Input & Output

Very different between CandJava

Very different between Cand C++

Handled by library functions in Cprintf()

scanf()

getc()

putc()

Many others!


17/24


and C

CS-2303, C-Term 2010 17

printf()Print formatted data

printf("string containing '%' specifiers",expr1, expr2, expr3, );

Copy the string, character-by-character, tothe output.

When the ith'%'is encountered, treat it as aconversion specifierfor converting the valueof expri

Copy the converted value to the output perinstructions encoded in the conversion specifier

Return number of characters printed


18/24


and C

CS-2303, C-Term 2010 18

printf()conversion specifiers

See K&R, p 154 & 244 or D&D Chapter 9 %d or%i

Treat expression as a decimal number (with sign)

%u Treat expression as unsigned decimal number

%f Treat expression as double precision floating point number; print

without exponent

%e or%E Treat expression as double precision floating point number; print with

exponent (base 10) scientific notation

%c Treat value of expression as the code for a single character

%s Treat expression as a pointer to a string

Later in this

course


19/24


and C

CS-2303, C-Term 2010 19

printf()conversion specifiers (continued)

Conversion specifiers may optionallycontain

Right or left alignment in the field

Minimum field width (padded on right or left) Precision i.e.,

Maximum length of string

Number of decimal places of floating point value

Examples%6dprint signed decimal number in 6-char field%8.4fprint floating point number with four places

after decimal point, field width of 8 characters


20/24


and C

CS-2303, C-Term 2010 20

scanf()Scan formatted data

scanf("string containing '%' specifiers",&var1, &var2, &var3, );

Scan the input, matching the string character bycharacter.

When the ith'%'is encountered, treat as aconversion specifierfor converting next sequenceof characters and storing result in vari

Copy the converted value to the output per instructions encodedin the conversion specifier

Stop if input does not match string or conversionnot successful

Return number of successful conversions.


21/24


and C

CS-2303, C-Term 2010 21

scanf()Typical Usage

int j;

double x;

scanf("%d%f", &j, &x);

Scan the input, skipping blanks and tabs

Try to match a signed integer; if successful, storeresult in j

Continue scanning, skipping blanks and tabs

Try to match a floating point number. If successful,store in x

Return number of items stored.


22/24


and C

CS-2303, C-Term 2010 22

scanf()Details

K&R Table B-2 (p. 246), D&D Chapter 9

printf()and scanf()are bothneeded for

Lab #1

Programming Assignment #1


23/24


and C

CS-2303, C-Term 2010 23

Summary

Differences and similarities between Java

and C Expressions

Statements

There are lotsof other differences Will be covered during the course


24/24


and C

CS-2303, C-Term 2010 24

Questions?

Differences Between C and Java

Documents

Transcript of Differences Between C and Java