Constructors & Destructors

When you create an object, you usually want to give it some starting values (like setting a player's health to 100). When an object is deleted, you might need to clean up memory. C++ handles this automatically using Constructors and Destructors.

1. The Constructor

• What it is: A special member function that is called automatically when an object is created.

• Rules: It must have the exact same name as the Class and it does not have a return type (not even void).

• Purpose: To initialize the object's attributes.

2. The Destructor

• What it is: A special function called automatically when an object goes out of scope or is deleted.

• Rules: Same name as the class but prefixed with a tilde (~). It takes no parameters.

• Purpose: To release memory or close files (clean up).

Code Example: Life Cycle of a Game Character

Notice how we don't manually call the Character() function; it happens the moment we declare the variable.

#include <iostream>
#include <string>
using namespace std;

class GameCharacter {
public:
    string name;
    int health;

    // 1. CONSTRUCTOR
    // Runs when: GameCharacter p1("Aragorn"); is called
    GameCharacter(string n) {
        name = n;
        health = 100;
        cout << "[System]: " << name << " has entered the world." << endl;
    }

    // 2. DESTRUCTOR
    // Runs when the program ends or the object is destroyed
    ~GameCharacter() {
        cout << "[System]: " << name << " has left the world (Object destroyed)." << endl;
    }

    void status() {
        cout << name << " Health: " << health << endl;
    }
};

int main() {
    cout << "--- Game Start ---" << endl;

    // Creating objects (This triggers the Constructor)
    GameCharacter p1("Warrior");
    p1.status();

    {
        // A temporary character in a smaller scope
        GameCharacter p2("Ghost");
        p2.status();
    } // p2 goes out of scope here (This triggers p2's Destructor)

    cout << "--- Game Ending ---" << endl;

    return 0;
} // p1's Destructor triggers here

Key Concept: Overloading Constructors

You can have multiple constructors for one class! For example, one that takes no names (default) and one that takes a name and a level. This gives you flexibility in how you "build" your objects.