How to Use Bitwise OR Operator in C: Syntax and Examples

In C, the bitwise OR operator is |. It compares each bit of two integers and returns a new integer where each bit is 1 if either bit of the operands is 1. Use it like result = a | b; to combine bits from a and b.

Syntax

The bitwise OR operator in C is written as |. It takes two integer operands and compares their bits one by one.

• Operand 1: First integer value.
• Operand 2: Second integer value.
• Result: Integer with bits set to 1 where either operand has a 1 bit.

c

result = operand1 | operand2;

Example

This example shows how to use the bitwise OR operator to combine bits of two numbers and print the result.

c

#include <stdio.h>

int main() {
    int a = 5;      // binary: 0101
    int b = 9;      // binary: 1001
    int result = a | b;  // bitwise OR

    printf("a = %d, b = %d\n", a, b);
    printf("a | b = %d\n", result);  // expected 13 (binary 1101)

    return 0;
}

Output

a = 5, b = 9
a | b = 13

Common Pitfalls

Common mistakes when using bitwise OR include:

• Using | instead of logical OR || when testing conditions.
• Applying bitwise OR to non-integer types without casting.
• Expecting decimal addition instead of bitwise combination.

Remember, | works on bits, not whole numbers as sums.

c

#include <stdio.h>

int main() {
    int x = 2;  // binary 0010
    int y = 4;  // binary 0100

    // Wrong: using bitwise OR instead of logical OR
    int wrong = x | y;  // result is 6 (binary 0110)

    // Correct: logical OR
    int correct = x || y; // result is 1 (true)

    printf("Bitwise OR result: %d\n", wrong);
    printf("Logical OR result: %d\n", correct);

    return 0;
}

Output

Bitwise OR result: 6
Logical OR result: 1

Quick Reference

Operator	Description	Example	Result
|	Bitwise OR	5 | 9	13 (binary 1101)
||	Logical OR (not bitwise)	5 || 9	1 (true)

Key Takeaways

Use the bitwise OR operator | to combine bits of two integers.

Bitwise OR sets each bit to 1 if either operand has a 1 bit in that position.

Do not confuse bitwise OR | with logical OR ||.

Bitwise OR works only on integer types and their bits.

Check your operands to avoid unexpected results from mixing logical and bitwise operators.