- Prison Code Breaker Diary -

My friend asked me for illustrating the idea of function pointer.
Then I wrote this small code for him.

/* HEADER */
#include <stdio.h>
/* DECLARE */
int Calculate( int, int, int (*pFunc)( int, int ) );

int Add( int, int );
int Sub( int, int );
int Mul( int, int );

/* MAIN */
int
main( int argc, char *argv[] )
{
   int (*p)(int, int) = NULL;

   printf("[ USING REFERENCE ]\n");
   printf("Result = %d\n", Calculate( 4, 5, &Add ) );
   printf("Result = %d\n", Calculate( 4, 5, &Sub ) );
   printf("Result = %d\n", Calculate( 4, 5, &Mul ) );  

   printf("[ USING POINTER ]\n");
   p = &Add;
   printf("P Result = %d\n", Calculate( 4, 5, p ) );
   p = ⋐
   printf("P Result = %d\n", Calculate( 4, 5, p ) );
   p = &Mul;
   printf("P Result = %d\n", Calculate( 4, 5, p ) );
   return 0;
}

/* DEFINITION */
int
Calculate( int a, int b, int (*pFunc)( int, int ) )
{
   return pFunc( a, b );
}

int Add( int a, int b )
{
   return ( a + b );
}

int Sub( int a, int b )
{
   return ( a - b );
}

int Mul( int a, int b )
{
   return ( a * b );
}