Various ways to swap two integer values in C

swap.c

#include <stdio.h>

void swap(int *, int *);
void swap_xor(int *, int *);

int main() {
    int a = 1, b = 2;

    printf("a = %i, b = %i\n", a, b);

    swap_xor(&a, &b);

    printf("a = %i, b = %i\n", a, b);
    return 0;
}

void swap(int *a, int *b) {
    *a = *a + *b;   // integer overflow
    *b = *a - *b;
    *a = *a - *b;
}

void swap_xor(int *a, int *b) {
    if (a == b)
        return;
    *a = *a ^ *b;
    *b = *b ^ *a;
    *a = *a ^ *b;
}

void swap_xor_short(int *a, int *b) {
    if (a == b)
        return;
    *a ^= *b;
    *b ^= *a;
    *a ^= *b;
}

void swap_xor_incorrect(int *a, int *b) {
    *a ^= *b ^= *a ^= *b;   // modification of lvalue w/out intervening sequence point
}