/* Author: ~swim~ Date: 3-Jan-2019 The code below demonstrates the use of Function Pointers and Function References. Use of Function Pointers is well known in C/C++ domain. But C++ also offers function calls through Function References. As with any other features of programming languages, Function References too have it's share of pros and cons Pros: 1. They cannot be null, so you can avoid checking for null references. 2. Like normal references, once assigned they too can't be changed, so you are sure that some other code cannot modify them intensionally or accidentally. Cons: 1. Like normal references, they must be initialized at the time of declaration. 2. Unlike Function Pointers you cannot easily create an "Array of" or a "Container of" Function References and pass them around other functions to achieve design flexibility. 3. Some may argue that function references are confusing especially with rvalue references(&&) available. Function pointers seems to convey the intent more clearly. Nevertheless they are provided as language facility so use them as per your design requirements. */ #include using namespace std; int Add(int arg1, int arg2) { return arg1 + arg2; } int main() { // P2F is a Pointer to a function taking // two integers as argument and // returning an int. // This is a new syntax (C++11 onwards) // old syntax // typedef int (*P2F)(int, int); using P2F = int (*)(int,int); // p2f is a variable of type P2F // We have defined a variable (p2f) and // assigned the address of function Add // to it. P2F p2f = Add; // or &Add, a function name is also a pointer, there is no need to explicitly use "address of" (&) operator. // call the function through function // pointer. Note most C Programmer are // used to the following syntax when // calling a function through function // pointer. // (*p2f)(10, 20); cout << "Calling Add(10, 20) through" " function poiner p2f \n\n"; cout << "Add(10,20) = " << p2f(10,20) << "\n\n"; // R2F is a Reference type to a // function taking two integers as // argument and returning an int. // This is a new syntax (C++11 onwards) // old syntax // typedef int (&R2F)(int, int); using R2F = int (&)(int, int); // r2f is a variable of type R2F // We have declared a variable of // type R2F and assigned a reference to // the function Add R2F r2f = Add; //&Add is invalid syntax // call the function through function // reference. // Note: (&r2f)(10,20) is also a valid // syntax cout << "Calling Add(10, 20) through" " function reference r2f \n\n"; cout << "Add(10,20) = " << r2f(10,20) << "\n\n"; return 0; }

Function Pointers and Function References.cpp