program9_03.c

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/* Program 9.3 Passing a Pointer to a function   */
#include <stdio.h>

/* Function prototypes */
int sum(int,int);
int product(int,int);
int difference(int,int);
int any_function(int(*pfun)(int, int), int x, int y);

int main(void)
{
  int a = 10;                         /* Initial value for a */
  int b = 5;                          /* Initial value for b */
  int result = 0;                     /* Storage for results */
  int (*pf)(int, int) = sum;          /* Pointer to function */

  /* Passing a pointer to a function */
  result = any_function(pf, a, b);

  printf("\nresult = %d", result );

  /* Passing the address of a function      */
  result = any_function(product,a, b);

   printf("\nresult = %d", result );

  printf("\nresult = %d\n", any_function(difference, a, b));
  return 0;
}

/* Definition of a function to call a function */
int any_function(int(*pfun)(int, int), int x, int y)
{
  return pfun(x, y);
}

/* Definition of the function sum        */
int sum(int x, int y)
{
  return x + y;
}

/* Definition of the function product    */
int product(int x, int y)
{
  return x * y;
}

/* Definition of the function difference */
int difference(int x, int y)
{
  return x - y;
}