Thread: Pointers: Please help to understand the code

Can anyone please explain the code: Don't understand why the author declared "z", even though it seems not being used?

Code:

#include <stdio.h>
void func(float *px, float *py) 
{   *px = 3 + 2 * *px;   *py = *py  - 21; }
int main()
{
 float x=0, y=4, z= 1; 
int i;
 func(&x, &y); 
func(&y, &z); 
printf("%f\n",y);
 return 0; 
}