It is the least expensive method to exchange the value of two Numbers without mediation. The simple principle is that the negative of xor is positive

Code:

#include <stdio.h>

int main()
{
 int a = 11, b = 22;
 printf("a=%d b=%d\n", a, b);
 a = a ^ b;
 b = a ^ b;
 a = a ^ b;
 printf("a=%d b=%d\n", a, b);
}

Compile: gcc test.c -o test

Perform: a=11 b=22 a=22 b=11