#include <stdio.h>

#define SIZE 10

// divides value by 2
void half (float *a)
{
  (*a) /= 2.0 ;
}

// multiplies value by 2
void twice (float *a)
{
  (*a) *= 2.0 ;
}

// applies function "func" to all elements of vector "v"
void apply (float *v, int n, void (*func) (float*))
{
  int i ;
  for (i=0; i< n; i++)
    func (&v[i]) ;
}

// prints a float vector
void printv (float *v, int n)
{
  int i ;
  for (i=0; i<n; i++)
    printf ("%6.1f", v[i]) ;
  printf ("\n") ;
}

int main ()
{
  float vet[SIZE] ;
  int i ;

  for (i=0; i<SIZE; i++)
    vet[i] = i*10 ;

  printv (vet, SIZE) ;

  // applies the function "half" to the vector
  apply (vet, SIZE, half) ;

  printv (vet, SIZE) ;

  // applies the function "twice" to the vector
  apply (vet, SIZE, twice) ;

  printv (vet, SIZE) ;

  return (0) ;
}