How to write an algorithm to swap values ?

/* part of work copied from http://www.sanfoundry.com/c-program-swap-values/ */
#include <stdio.h>

swap_values()
{
int temp;
int *ptr1, *ptr2;
int a, b;
printf("Enter integer values to be swapped: ");
scanf("%d %d",&a,&b);
ptr1 = &a;
ptr2 = &b;
temp = *ptr1;
*ptr1 = *ptr2;
*ptr2 = temp;
printf("Swapped values are: %d %d \n",a,b);
}

/* http://www.programmingsimplified.com/c-program-swap-two-numbers */
/* http://betterexplained.com/articles/swap-two-variables-using-xor/ */
/* http://www.science.unitn.it/~fiorella/guidelinux/tlk/node27.html */