function pointer.c

//**********************************************************************
//**  Easy Example for describing the usage of function pointer in C  **
//**********************************************************************
#include<stdio.h>

//A simple funtion which return its parameter.
int p(int x){ return x ;}

typedef int (*functionPointer)(int x) ;
typedef struct _Interface {
   functionPointer fp ;
} Interface ;

//A instance of Interface.
Interface myItf = { p } ;

//---MAIN:
int main(){
   // Instance usage.
   int a = myItf.fp(10) ;
   //A pointer to a Interface instance.
   Interface *iface = &myItf ;
   
   // Isn't it like the member funtion calling in C++ O-O language !?
   int b = iface->fp(11) ;
   int c = (*iface).fp(12) ; 
   
   printf("a=%d\n",a);
   printf("b=%d\n",b);
   printf("c=%d\n",c);
	return 0;
}

//---OUTPUT:
/*
   a=10
   b=11
   c=12

 * */