Зміст курсу

C++ OOP

1. Fundamentals of OOP in C++

Introduction to Object-Oriented Programming in C++Why use Object-Oriented Programming?Class Creation Syntax Attributes of the Class Methods of the Class Static Members of The Class The This Keyword Classes and Objects Overview

2. Constructors and Destructors

What is a Constructor of the Class Constructor and Attributes Constructor Initialization List Initialization List Practice Constructor Delegation Constructor Delegation Practice What is a Destructor of the Class Constructors and Destructors Practice

3. Encapsulation Overview

Introduction to Encapsulation Access Modifiers Keywords Access Modifiers Practice Accessor and Mutator Methods Segmentation and Aggregation The Friend Keyword

4. Inheritance Overview

Introduction to Inheritance Access Modifiers in Inheritance Mulptiple Inheritance Constructor and Destructor in Inheritance Diamond Inheritance The Final Keyword

5. Polymorphism Overview

Introduction to Polymorphism Virtual and Override Keywords Pure Virtual Method Operator Overloading

Constructor and Destructor in Inheritance

Base Class Constructor First

In the context of inheritance, constructors play a vital role in initializing derived classes correctly. Understanding the sequence in which constructors are invoked is key to grasping inheritance dynamics. Look at the output of the code snippet below to see the order of constructors calls.

main.cpp


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#include <iostream>

class Base {
public:
    Base() { std::cout << "Base constructor called" << std::endl; }
};

class Derived : public Base {
public:
    Derived() { std::cout << "Derived constructor called" << std::endl; }
};

int main()
{
    Derived derivedObj;
}

Note

Once the Base Class constructor has completed its initialization, the Derived Class constructor is executed.

The superclass is called first because it has to initialize the inherited members of the subclass. This ensures that the subclass starts with a valid state and can rely on the initialized state of its base class.

main.cpp


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class Base {
public:
    Base(int value) 
        : data(value) {}
private:
    int data;
};

class Derived : public Base {
public:
    Derived(int value) 
        : Base(value) {}
};

int main()
{

}

In the example, you call the constructor with parameters in the initializer list. You have to explicitly call the superclass constructor within the initializer list of the subclass constructor. If you don't specify a base class constructor in the initializer list, the default constructor of the superclass is called automatically.

Derived Class Destructor First

When an object is destroyed, destructors are invoked in the reverse order of their constructors. This means that destructors are called for the most derived class first, then for each base class in reverse order of their declaration.

main.cpp


              12345678910111213141516
            
#include <iostream>

class Base {
public:
    ~Base() { std::cout << "Base destructor called" << std::endl; }
};

class Derived : public Base {
public:
    ~Derived() { std::cout << "Derived destructor called" << std::endl; }
};

int main()
{
    Derived derivedObj;
}

Note

Only after the Derived Class destructor has finished its cleanup, the Base Class destructor is invoked.

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Зміст курсу

C++ OOP

1. Fundamentals of OOP in C++

2. Constructors and Destructors

3. Encapsulation Overview

Introduction to Encapsulation Access Modifiers Keywords Access Modifiers Practice Accessor and Mutator Methods Segmentation and Aggregation The Friend Keyword

4. Inheritance Overview

Introduction to Inheritance Access Modifiers in Inheritance Mulptiple Inheritance Constructor and Destructor in Inheritance Diamond Inheritance The Final Keyword

5. Polymorphism Overview

Introduction to Polymorphism Virtual and Override Keywords Pure Virtual Method Operator Overloading

Constructor and Destructor in Inheritance

Base Class Constructor First

main.cpp


              12345678910111213141516
            
#include <iostream>

class Base {
public:
    Base() { std::cout << "Base constructor called" << std::endl; }
};

class Derived : public Base {
public:
    Derived() { std::cout << "Derived constructor called" << std::endl; }
};

int main()
{
    Derived derivedObj;
}

Note

Once the Base Class constructor has completed its initialization, the Derived Class constructor is executed.

main.cpp


              123456789101112131415161718
            
class Base {
public:
    Base(int value) 
        : data(value) {}
private:
    int data;
};

class Derived : public Base {
public:
    Derived(int value) 
        : Base(value) {}
};

int main()
{

}

Derived Class Destructor First

main.cpp


              12345678910111213141516
            
#include <iostream>

class Base {
public:
    ~Base() { std::cout << "Base destructor called" << std::endl; }
};

class Derived : public Base {
public:
    ~Derived() { std::cout << "Derived destructor called" << std::endl; }
};

int main()
{
    Derived derivedObj;
}

Note

Only after the Derived Class destructor has finished its cleanup, the Base Class destructor is invoked.

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Секція 4. Розділ 4