//  File: fptr.C
//
//  Exploring function pointers.

#include <stdio.h>

// some simple functions

int add3(int n) {
   return n + 3 ;
}

int add5(int n) {
   return n + 5 ;
}


// Takes a function parameter

int apply (int addx(int), int m) {
   return addx(m) ;
}

main() {
   int m = 2, result ; 

   // func is a variable that holds the address of a function
   // which takes an int parameter and returns an int.
   //
   int (*func)(int) ;

   printf("m + 3 = %d\n", add3(m) ) ;
   printf("m + 5 = %d\n", add5(m) ) ;
   printf("\n") ;

   result = apply(&add3, m) ;
   printf("Applying add3 to m = %d\n", result) ; 
   result = apply(&add5, m) ;
   printf("Applying add5 to m = %d\n", result) ; 
   printf("\n") ;

   func = &add3 ;
   result = apply(func, m) ;
   printf("Applying func to m = %d\n", result) ; 

   func = &add5 ;
   result = apply(func, m) ;
   printf("Applying func to m = %d\n", result) ; 
}