C Bitwise Operators

Bitwise operators work on the individual bits of integers: & (and), | (or), ^ (xor), ~ (not), << and >> (shift). They are used for flags, masks and low-level protocols.

ExampleC

#include <stdio.h>

int main(void) {
  unsigned int a = 12;  // 1100
  unsigned int b = 10;  // 1010
  printf("%u\n", a & b);   // 8  (1000)
  printf("%u\n", a | b);   // 14 (1110)
  printf("%u\n", a ^ b);   // 6  (0110)
  printf("%u\n", a << 2);  // 48
  printf("%u\n", a >> 1);  // 6

  unsigned int flags = 0;
  flags |= 1 << 0;          // set bit 0
  flags |= 1 << 3;          // set bit 3
  printf("flags=%u\n", flags);
  printf("bit 3 set? %d\n", (flags & (1 << 3)) != 0);
  flags &= ~(1 << 0);       // clear bit 0
  printf("flags=%u\n", flags);
  return 0;
}

Output

8
14
6
48
6
flags=9
bit 3 set? 1
flags=8

Quick check

What does x << 2 do to an integer?

Multiplies it by 4Adds 2Divides it by 2

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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