#include <stdio.h>

typedef float * floatptr;

void swapfloats(floatptr a, floatptr b) {
    float temp; /* This is still float, because we are swapping floats */
    temp = *a;  /* Note the '*'s - get the float pointed to by a. */
    *a = *b;    /* Copy the float b points at into the variable a points at*/
    *b = temp;  /* Copy the float in temp into the variable b points at. */
}

main() {
    float first=2, second=1;
    swapfloats(&first,&second);    /* Note the 'address-of' operators */
    printf("%f  %f\n", first, second);
    return 0;
}