Logical Operators in C

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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 the condition becomes true.	(A && B) is false.
||	Called Logical OR Operator. If any of the two operands is non-zero, then the condition becomes true.	(A || B) is true.
!	Called Logical NOT Operator. It is used to reverse the logical state of its operand. If a condition is true, then Logical NOT operator will make it false.	!(A && B) is true.

Example

Try the following example to understand all the logical operators available in C −

#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 the following result −

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