C Language | Introduction to C | Bit Operations

Bitwise operators manipulate individual bits in integer values.

Bitwise Operators

AND produces 1 only when both bits are 1. It is useful for extracting selected bits with a mask.

  0101 1100
& 0000 1111
------------
  0000 1100

Code 1

#include <stdio.h>

int main() {
 char ch5 = '5';
 printf("ch5: %%c = %c, %%X = %X, numeric = %d\n" , ch5 , ch5 , ch5 & 0x0F);
 return 0;
}

OR produces 1 when either bit is 1. XOR produces 1 when the two bits differ. Complement reverses every bit.

Code 2

#include <stdio.h>

int main() {
 unsigned int value = 0xCC33CC33;
 printf("~%X = %X\n" , value , ~value);
 return 0;
}

Bit Shifts

Shift operators move bits left or right.

value << count
value >> count

For unsigned values, shifting left by one position corresponds to multiplication by two when no significant bit is discarded. Shifting right by one corresponds to division by two.

Code 3

#include <stdio.h>

int main() {
 unsigned int value = 100;
 printf("value / 4 = %u\nvalue * 4 = %u\n" , value >> 2 , value << 2);
 return 0;
}

Use unsigned values when portable bit manipulation matters. Right-shifting a negative signed integer is implementation-defined, and shifts that exceed the valid width must be avoided.