#include <stdio.h>

void swap(char* a, char* b) {
    *a ^= *b;
    *b ^= *a;
    *a ^= *b;
}

int main(int argc, char* argv[]) {
	char a = 11;
    char b = 15;
    printf("a = %d, b = %d", a, b);
    swap(&a, &b);
    printf("a = %d, b = %d", a, b);
    return 0;
}