Logical Operators in C

Following table shows all the logical operators supported by C language. Assume variable A holds 1 and variable B holds 0 then:

Operator	Description	Example
&&	Called Logical AND operator. If both the operands are non zero then condition becomes true.	(A && B) is false.
||	Called Logical OR Operator. If any of the two operands is non zero then condition becomes true.	(A || B) is true.
!	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is true.

Example

Try following example to understand all the logical operators available in C programming language:

#include <stdio.h>

main()
{
   int a = 5;
   int b = 20;
   int c ;

   if ( a && b )
   {
      printf("Line 1 - Condition is true\n" );
   }
   if ( a || b )
   {
      printf("Line 2 - Condition is true\n" );
   }
   /* lets change the value of  a and b */
   a = 0;
   b = 10;
   if ( a && b )
   {
      printf("Line 3 - Condition is true\n" );
   }
   else
   {
      printf("Line 3 - Condition is not true\n" );
   }
   if ( !(a && b) )
   {
      printf("Line 4 - Condition is true\n" );
   }
}

When you compile and execute the above program it produces following result:

Line 1 - Condition is true
Line 2 - Condition is true
Line 3 - Condition is not true
Line 4 - Condition is true