C - Bitwise XOR and assignment operator

The Bitwise XOR and assignment operator (^=) assigns the first operand a value equal to the result of Bitwise XOR operation of two operands.

(x ^= y) is equivalent to (x = x ^ y)

The Bitwise XOR operator (^) is a binary operator which takes two bit patterns of equal length and performs the logical exclusive OR operation on each pair of corresponding bits. It returns 1 if only one of the bits is 1, else returns 0.

The example below describes how bitwise XOR operator works:

50 ^ 25 returns 43

     50    ->    110010  (In Binary)
   ^ 25    ->  ^ 011001  (In Binary)
    ----        --------
     43    <-    101011  (In Binary)  

The code of using Bitwise XOR and assignment operator (^=) is given below:

#include <stdio.h>
 
int main (){
  int x = 50;
  int y = 25;

  //Bitwise XOR and assignment operation
  x ^= y;

  //Displaying the result
  printf("x = %d", x);
  return 0;
}

The output of the above code will be:

x = 43

Example: Swap two numbers without using temporary variable

The bitwise XOR and assignment operator can be used to swap the value of two variables. Consider the example below.

#include <stdio.h>

static void swap(int x, int y) {
  printf("Before Swap.\n");
  printf("x = %d\n", x);
  printf("y = %d\n", y);

  //Swap technique
  x ^= y;
  y ^= x;
  x ^= y;

  printf("After Swap.\n");
  printf("x = %d\n", x);
  printf("y = %d\n", y);
}

int main() {
  swap(10, 25);
  return 0;
}

The above code will give the following output:

Before Swap.
x = 10
y = 25
After Swap.
x = 25
y = 10