Unit 4: Operators and Expression

Arithmetic operators

Arithmetic operators perform basic mathematical operations on numeric operands.

Operator	Operation	Example
+	Addition	a + b
-	Subtraction	a - b
*	Multiplication	a * b
/	Division	a / b
%	Modulus	a % b

#include <stdio.h>

int main(void)
{
    int a = 10, b = 3;
    printf("a + b = %d\n", a + b);
    printf("a - b = %d\n", a - b);
    printf("a * b = %d\n", a * b);
    printf("a / b = %d\n", a / b);
    printf("a %% b = %d\n", a % b);
    return 0;
}

Relational operators

Relational operators compare two values and return either 1 (true) or 0 (false).

Operator	Meaning
<	Less than
>	Greater than
<=	Less than or equal
>=	Greater than or equal
==	Equal to
!=	Not equal to

#include <stdio.h>

int main(void)
{
    int a = 5, b = 10;
    printf("%d\n", a < b);   /* 1 */
    printf("%d\n", a == b);  /* 0 */
    return 0;
}

Logical and Boolean operators

Logical operators are used to combine relational expressions.

Operator	Meaning
&&	Logical AND
||	Logical OR
!	Logical NOT

#include <stdio.h>

int main(void)
{
    int age = 20;
    if (age >= 18 && age <= 60)
        printf("Eligible\n");
    return 0;
}

Assignment operators

The assignment operator = stores the value of the right-hand expression in the variable on the left. C also provides compound assignment operators.

Operator	Equivalent to
+=	a = a + b
-=	a = a - b
*=	a = a * b
/=	a = a / b
%=	a = a % b

int a = 10;
a += 5;  /* a = 15 */
a *= 2;  /* a = 30 */

Ternary operator

The ternary operator (? :) is a shorthand for an if-else statement.

condition ? expr1 : expr2;

If condition is true, the expression evaluates to expr1; otherwise to expr2.

#include <stdio.h>

int main(void)
{
    int a = 10, b = 20;
    int max = (a > b) ? a : b;
    printf("Max = %d\n", max);
    return 0;
}

Bit-wise operators

Bit-wise operators work on the binary representation of integers.

Operator	Meaning
&	Bit-wise AND
|	Bit-wise OR
^	Bit-wise XOR
~	Bit-wise complement
<<	Left shift
>>	Right shift

#include <stdio.h>

int main(void)
{
    int a = 12, b = 10;        /* 1100 and 1010 */
    printf("a & b = %d\n", a & b);  /* 1000 = 8  */
    printf("a | b = %d\n", a | b);  /* 1110 = 14 */
    printf("a ^ b = %d\n", a ^ b);  /* 0110 = 6  */
    printf("a << 1 = %d\n", a << 1);
    printf("a >> 1 = %d\n", a >> 1);
    return 0;
}

Increment and decrement operators

• ++ increases the value of a variable by 1.
• -- decreases the value of a variable by 1.

They can be used in prefix form (++a) or postfix form (a++).

• Prefix: increment/decrement first, then use the value.
• Postfix: use the value first, then increment/decrement.

#include <stdio.h>

int main(void)
{
    int a = 5;
    printf("%d\n", ++a);  /* 6 (prefix)  */
    printf("%d\n", a++);  /* 6 (postfix) */
    printf("%d\n", a);    /* 7           */
    return 0;
}