Logical operators in C

C programming logical operators; Through this tutorial, you will learn in detail about logical operators in c programming and how to use these operators.

Note that:- Logical operators are commonly used in decision-making in C programming.

Logical Operators in C

Logical operators are used to performing logical operations of given expressions (relational expressions) or variables.

Types of Logical Operators in C

See the following table for types of logical operators in c programming:

Operator	Meaning	Example
&&	Logical AND. True only if all operands are true	If c = 5 and d = 2 then, expression ((c==5) && (d>5)) equals to 0.
||	Logical OR. True only if either one operand is true	If c = 5 and d = 2 then, expression ((c==5) || (d>5)) equals to 1.
!	Logical NOT. True only if the operand is 0	If c = 5 then, expression !(c==5) equals to 0.

There are examples of logical operators in C. See the following example:

Example 1 – Logical Operators in C

#include<stdio.h>

int main()
{
    int a = 5, b = 10 ,ret;

    ret = ( (a <= b) || (a != b) ); 
    // 5 <= 10 ==> true. 5 != 10 ==> true. So, 1 || 1 will return 1.
    printf("Return value of above expression is %d\n",ret);

    ret = ( ( a < b) && (a == b ) ); 
    // 5 < 10 ==>true. 5 == 10 ==> false. So, 1 && 0 will return 0;
    printf("Return value of above expression is %d\n",ret);

    ret = ! ( ( a < b) && (a == b ) ); 
    /*we have used the same expression here.
     And its result was 0.
     So !0 will be 1.*/
    printf("Return value of above expression is %d\n",ret);

    return 0;
}

Output

Return value of above expression is 1
Return value of above expression is 0
Return value of above expression is 1

Example 2 – Logical Operators in C

#include <stdio.h>
 
int main()
{
   int m=40,n=20;
   int o=20,p=30;
   if (m>n && m !=0)
   {
      printf("&& Operator : Both conditions are true\n");
   }
   if (o>p || p!=20)
   {
      printf("|| Operator : Only one condition is true\n");
   }
   if (!(m>n && m !=0))
   {
      printf("! Operator : Both conditions are true\n");
   }
   else
   {
      printf("! Operator : Both conditions are true. " \
      "But, status is inverted as false\n");
   }
}

Output

&& Operator : Both conditions are true
|| Operator : Only one condition is true
! Operator : Both conditions are true. But, status is inverted as false

Example 3 – Logical Operators in C

// Working of logical operators

#include <stdio.h>
int main()
{
    int a = 5, b = 5, c = 10, result;

    result = (a == b) && (c > b);
    printf("(a == b) && (c > b) is %d \n", result);

    result = (a == b) && (c < b);
    printf("(a == b) && (c < b) is %d \n", result);

    result = (a == b) || (c < b);
    printf("(a == b) || (c < b) is %d \n", result);

    result = (a != b) || (c < b);
    printf("(a != b) || (c < b) is %d \n", result);

    result = !(a != b);
    printf("!(a != b) is %d \n", result);

    result = !(a == b);
    printf("!(a == b) is %d \n", result);

    return 0;
}

Output

(a == b) && (c > b) is 1 
(a == b) && (c < b) is 0 
(a == b) || (c < b) is 1 
(a != b) || (c < b) is 0 
!(a != b) is 1 
!(a == b) is 0