#include <stdio.h>
#include <stdlib.h>

float compute1(float x) {
  fprintf(stdout, "\t... entering compute 1 ...\n");
  return x * x * x + 27.0;
}

float power(float x) {
  fprintf(stdout, "\t... entering power ...\n");
  return x * x * x;
}

float compute2(float x, float (*fct)(float)) {
    fprintf(stdout, "\t... entering compute 2 ...\n");
    return (fct)(x);
}

int main(int argc, char** argv) {

  float x = 3;

  fprintf(stdout, "1. call the function directly: f(%f) = %f\n",
	  x, compute1(x));

  // declare a function pointer to compute1 here
  //
  float (*foo)(float);
  foo = &compute1;

  // call foo here
  //
  fprintf(stdout, "2. call compute1 using a function pointer: f(%f) = %f\n",
	  x, foo(x));

  // call foo here
  //
  fprintf(stdout, "3. call compute1 by passing a function pointer to compute2: f(%f) = %f\n",
	  x, compute2(x, foo));
}