The bitwise operators available in C are,
bitwise AND – ‘&’
bitwise OR – ‘|’
bitwise XOR – ‘^’
left-shift operator – ‘<<’
right-shift operator – ‘>>’
bitwise NOT (1’s complement) – ‘~’
This C program shows some of common usage of the bitwise operators. The bitwise operators are widely used in embedded C programming.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | #include <stdio.h> int main(void) { int x = 0x1u; // Set 2nd bit x |= (1u << 2); printf("%d\n", x); // Clear 2nd bit x &= ~(1u << 2); printf("%d\n", x); // Toggle 2nd bit x ^= (1 << 2); printf("%d\n", x); // Test 2nd bit x & (1u << 2) ? puts("true") : puts("false"); return 0; } |
Code walk-through
The code fragment x |= (1u << 2); sets the 2nd bit by shifting the value 1 left by 2 positions. Similarly the code fragment x &= ~(1u << 2);clears the second bit by shifting the value 1 by 2 positions to the left and doing a 1’s complement.
The line x ^= (1 << 2); toggles the 2nd bit by left shifting the value 1 by 2 positions and XORing with the value to be modified.
The code fragment x & (1u << 2) ? puts("true") : puts("false"); tests the bit at position 2 by creating a mask by shifting 1 by 2 positions to the left and use the bit-wise & operator to check if the result is not 0 or otherwise.
