What is Logical Operators in c?



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In C programming, logical operators are used to perform logical operations on boolean values or expressions.

Operator Description Example Result
&& AND Operator a < b && b < c True if both conditions are true, False otherwise.
|| OR Operator a < b || b > c True if at least one condition is true, False otherwise.
! NOT Operator !(a > b) True if the condition is false, False otherwise.


1. Logical AND Operator (&&) Program:

This program evaluates whether both conditions a < b and b < c are true. If both conditions are true, it returns 1 otherwise it returns 0.

#include <stdio.h>

int main() {
    int a = 5, b = 10, c = 15;
    
    // Using && operator
    printf("Result of logical AND: %d\n", (a < b && b < c));
    
    return 0;
}
Output: 
Result of logical AND: 1


2. Logical OR Operator (||) Program:

This program checks if at least one of the conditions a < b or b > c is true. If either condition is true, it returns 1; otherwise, it returns 0.

#include <stdio.h>

int main() {
    int a = 5, b = 10, c = 15;
    
    // Using || operator
    printf("Result of logical OR: %d\n", (a < b || b > c));
    
    return 0;
}
Output: 
Result of logical OR: 1


3. Logical NOT Operator (!) Program:

This program negates the truth value of the expression a > b. If a > b is false, it returns 1 if true it returns 0.

#include <stdio.h>

int main() {
    int a = 5, b = 10;
    
    // Using ! operator
    printf("Result of logical NOT: %d\n", !(a > b));
    
    return 0;
}
Output: 
Result of logical NOT: 1

Short-Circuiting Operation in Logical Operators:


In case of logical AND, the second operand is not evaluated if first operand is false. For example, program 1 below doesn't print Short-Circuiting in Logical Operators as the first operand of logical AND itself is false. 

#include <stdio.h>
#include <stdbool.h>
int main()
{
    int a=10, b=4;
    bool res = ((a == b) && printf("Short-Circuiting in Logical Operators"));
    return 0;
}
Output: 
Will Print Nothing

But below program prints Logical AND Operator because first operand of logical AND (&&) is true.


#include <stdio.h>
#include <stdbool.h>
int main()
{
    int a=10, b=4;
    bool res = ((a != b) && printf("Logical AND Operator"));
    return 0;
}
Output: 
Logical AND Operator

In case of logical OR, the second operand is not evaluated if first operand is true. For example, program below will not print any thing because first Logical condition is true. 

         #include <stdio.h>
        #include <stdbool.h>
        int main()
        {
            int a=10, b=4;
            bool res = ((a != b) || printf("Logical AND Operator"));
            return 0;
Output: 

            --------------------------------
            Process exited after 0.06589 seconds with return value 0
            Press any key to continue . . .
Example:9
But below program prints Logical Operator as first operand of logical OR is false. 

         #include <stdio.h>
        #include <stdbool.h>
        int main()
        {
            int a=10, b=4;
            bool res = ((a == b) || printf("Logical Operator"));
            return 0;
        }
Output: 
        Logical Operator
        --------------------------------
        Process exited after 0.04 seconds with return value 0
        Press any key to continue . . .




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