#include using namespace std; class Identity { public: // declare a constructor without define the argument Identity(string n, int a, string c); private: string name; // declare name int age; // declare age string country; // declare country }; // make a member initialization list that also has a constructor and it will initializes the members. Identity::Identity(string n, int a, string c) : name(n), age(a), country(c) /* How the code work is almost same like this.. name = string n age = int a country = string c */ { // this scope will be automatically called when the object are created (Constructor) and this is the argument from constructor Identity cout << "Name = " << name << endl; cout << "Age = " << age << endl; cout << "Country = " << country << "\n\n"; } int main() { // Syntax = Class Obj(name,age,country); Identity ardian("Ardian Anwar", 18, "Indonesia"); Identity kim("Kim Lewis", 15, "United States"); Identity mizuki("Mizuki Kazane", 17, "Japan"); Identity deny("Deny Haryanto", 17, "Indonesia"); Identity sally("Sally McSalad", 16, "Sweden"); } /***************************************************** * Why do we need to use member initializer? * * * * Because its not just the matter of writting style, * * it has different performance and functionality. * * on some condition. The specific example is classes.* * * *****************************************************/ /* Explanation step by step how the code works. First we will excute Identity ardian("Ardian Anwar", 18, "Indonesia"); After that, the compiler will matching the object and it match with Identity(string n, int a, string c); Remember Identity(string n, int a, string c); only declare a function (Its like telling the compiler this function is exist). Then the compiler will look for the argument and we found it with... Identity::Identity(string n, int a, string c) : name(n), age(a), country(c) { some code... } The compiler will initialize that and excute the code between curly brackets. After done, it will return to main and excute the next line. i hope you understood it well :) */

An example class on C++ with initialization list (Explanation)