C OR Logical Operator

C OR Logical Operator is used to compute logical OR operation between two boolean values. The operands to OR Operator can be boolean variables, or conditions that return a boolean value, or integers equivalent to the boolean values.

C OR Operator takes two boolean values as operands and returns an int value equivalent to the resulting boolean value .

operand_1 || operand_2

Truth Table

The truth table of OR Logical Operator is

Operand 1Operand 2Returns
truetrue1
truefalse1
falsetrue1
falsefalse0

C OR returns true if at-least one of the operand is true.

Integer value of 1 is equivalent to true, and 0 is equivalent to false.

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Examples

The following example demonstrates the usage of OR logical operator with different boolean values.

main.c

#include <stdio.h>
#include <stdbool.h>

int main() {
    bool x, y, result;
    
    x = true;
    y = true;
    result = x || y;
    printf("%d || %d : %d\n", x, y, result);
    
    x = true;
    y = false;
    result = x || y;
    printf("%d || %d : %d\n", x, y, result);
    
    x = false;
    y = true;
    result = x || y;
    printf("%d || %d : %d\n", x, y, result);
    
    x = false;
    y = false;
    result = x || y;
    printf("%d || %d : %d\n", x, y, result);
}

Output

1 || 1 : 1
1 || 0 : 1
0 || 1 : 1
0 || 0 : 0
Program ended with exit code: 0

The following example demonstrates the usage of OR logical operator in combining boolean conditions and forming a compound condition.

main.c

#include <stdio.h>

int main() {
    int a = 7;
    
    if ((a < 10) || (a % 2 == 0)) {
        printf("%d is even, or less than 10.\n", a);
    }
}

Output

7 is even, or less than 10.
Program ended with exit code: 0

In the above example, a < 10 is a condition that checks if a is less than 10 and a % 2 == 0 is another condition that checks if a is even number.

If we would like to check if either of the conditions a < 10 or a % 2 == 0 is true, we use OR Logical Operator.

Conclusion

In this C Tutorial, we learned what C OR Logical Operator is, and how to use it with conditional expressions.