Thread: pointers swap function

Need to write a function with 2 floats that make the first argument "a - b" and the second one "b - a", then print the 2 with .2 precision.
Compiles but output is not correct.
Can anyone tell me why? and maybe suggest me a book with a good pointers chapter? My slides are confusing.

This is my code.

Code:

#include <stdio.h>


float diff_abs(float*, float*);


float diff_abs(float *a, float *b)
{
    *a = *a - *b;
    *b = *b - *a;
}


int main(void)
{
    float x;
    float y;
    scanf("%f", &x);
    scanf("%f", &y);
    diff_abs(&x,&y);
    printf("%.2f\n", x);
    printf("%.2f", y);
    return 0;
}

Thanks in advance.