C language-function pointer and function pointer array __ function

#include <stdio.h>
//function pointer 
int fun (void)
{
	printf ("Hello world\n");
	return 0;
}

int main (int argc, const char *argv[])
{
	printf ("main =%p\n", main);
	Int (*p) (void) = fun; 			P 	function pointer: Essence is pointer								
	p (); 							Fun 	Address constant return
	0;
}

#include <stdio.h>
//function pointer array 

//function Sub 
int sub (int a, int b)
{
	printf ("Sub =%d\n", a-b); C22/>return 0;
}
function add 
int Add (int a, int b)
{
	printf ("add =%d\n", a+b);
	return 0;
}
int main (int argc, const char *argv[])
{
	//define an array of function pointers  : Its invocation return value is int, parameter is int,int 
	int (*p[2]) (int, int ); Essence: Array, element: function pointer type												
	p[0] = sub;
	P[1] = add;

	P[1] (10,3);
	P[0] (10,3);
	return 0;
}