Classes and Objects

Defining a Class

class MyClass {
  public:             // Access specifier
    int myNum;        // Attribute (int variable)
    string myString;  // Attribute (string variable)
};

Creating an Object

MyClass myObj;  // Create an object of MyClass

myObj.myNum = 15;          // Set the value of myNum to 15
myObj.myString = "Hello";  // Set the value of myString to "Hello"

cout << myObj.myNum << endl;         // Output 15
cout << myObj.myString << endl;      // Output "Hello"

Constructors

class MyClass {
  public:
    int myNum;
    string myString;
    MyClass() {  // Constructor
      myNum = 0;
      myString = "";
    }
};

MyClass myObj;  // Create an object of MyClass

cout << myObj.myNum << endl;         // Output 0
cout << myObj.myString << endl;      // Output ""

Destructors

class MyClass {
  public:
    int myNum;
    string myString;
    MyClass() {  // Constructor
      myNum = 0;
      myString = "";
    }
    ~MyClass() {  // Destructor
      cout << "Object destroyed." << endl;
    }
};

MyClass myObj;  // Create an object of MyClass

// Code here...

// Object is destroyed automatically when the program exits the scope

Class Methods

class MyClass {
  public:
    int myNum;
    string myString;
    void myMethod() {  // Method/function defined inside the class
      cout << "Hello World!" << endl;
    }
};

MyClass myObj;  // Create an object of MyClass
myObj.myMethod();  // Call the method

Access Modifiers

class MyClass {
  public:     // Public access specifier
    int x;    // Public attribute
  private:    // Private access specifier
    int y;    // Private attribute
  protected:  // Protected access specifier
    int z;    // Protected attribute
};

MyClass myObj;
myObj.x = 25;  // Allowed (public)
myObj.y = 50;  // Not allowed (private)
myObj.z = 75;  // Not allowed (protected)

Getters and Setters

class MyClass {
  private:
    int myNum;
  public:
    void setMyNum(int num) {  // Setter
      myNum = num;
    }
    int getMyNum() {  // Getter
      return myNum;
    }
};

MyClass myObj;
myObj.setMyNum(15);  // Set the value of myNum to 15
cout << myObj.getMyNum() << endl;  // Output 15

Inheritance

class Vehicle {
  public:
    string brand = "Ford";
    void honk() {
      cout << "Tuut, tuut!" << endl;
    }
};

class Car : public Vehicle {
  public:
    string model = "Mustang";
};

Car myCar;
myCar.honk();  // Output "Tuut, tuut!"
cout << myCar.brand + " " + myCar.model << endl;  // Output "Ford Mustang"

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