Function_Pointers.cpp

// Function_Pointers.cpp : This file contains the 'main' function. Program execution begins and ends there.
//


#include "pch.h"
#include <iostream>
#include <string>
using namespace std;

int add()
{
	int i = 10;
	cout << "inside add" << endl;
	return i = i + i;
}
double divide()
{
	double j = 7;
	return j / 9;
}
int square(int x)
{
	return x * x;
}
void NonRetFunc()
{
	cout << "Non Ret Func" << endl;
	//return 0;
}
double bigfunc(int(*fcnPtr1)(), double(*fcnPtr4)())
{

	return ((*fcnPtr1)() + (*fcnPtr4)());
}
int main()
{
	cout << "Function pointers" << endl;
	if (add)//as the check is against the addr of add()
	{
		cout << "This is always true!" << endl;
	}

	if (int i = add() > 100)//check is done against ret value of add()
	{
		cout << "> 100" << endl;
	}
	else
		cout << "<< 100" << endl;

	// function pointer assignments
	int(*fcnPtr1)() = add; // okay
	//int(*fcnPtr2)() = divide; // wrong -- return types don't match!
	double(*fcnPtr4)() = divide; // okay
	//fcnPtr1 = square; // wrong -- fcnPtr1 has no parameters, but hoo() does
	int(*fcnPtr3)(int) = square; // okay
	void(*fcnPtr5)() = NonRetFunc;
	double(*fcnPtr6)(int(*fcnPtr1)(), double(*fcnPtr4)()) = bigfunc; // use if a func ptr is used to access bigfunc


	cout << "add 10 and 10 is " << (*fcnPtr1) << endl;//ret the addr of add
	cout << "add 10 and 10 is " << (*fcnPtr1)() << endl;
	cout << "divide 7 with 9 is " << (*fcnPtr4)() << endl;
	cout << "square 9 is " << (*fcnPtr3)(9) << endl;
	(*fcnPtr5)();
	cout << "bigfunc result is " << (*fcnPtr6)(add, divide) << endl;
	cout << "bigfunc result is " << bigfunc(add, divide) << endl;
	getchar(); //added to prevent console from closing after code is executed.
}