Constructor calling order in C++ - Mini Project: Build & Apply

Constructor calling order

📖 Scenario: Imagine you are building a simple program to understand how constructors are called in a class inheritance setup in C++. This helps you see the order in which parts of an object are created.

🎯 Goal: You will create two classes: Base and Derived. You will write constructors for both that print messages when called. Then you will create an object of Derived and observe the order of constructor calls.

📋 What You'll Learn

Create a class called Base with a constructor that prints "Base constructor called".

Create a class called Derived that inherits from Base with a constructor that prints "Derived constructor called".

Create an object of type Derived in the main function.

Print the messages exactly as specified to observe the constructor calling order.

💡 Why This Matters

🌍 Real World

Understanding constructor calling order helps when designing classes that inherit from others, ensuring proper initialization.

💼 Career

Many software jobs require knowledge of object-oriented programming and class inheritance, especially in C++ development.

1

Create the Base class with a constructor

Create a class called Base with a constructor that prints "Base constructor called".

C++

# Create class Base with a constructor that prints "Base constructor called"
// Your code here

Need a hint?

Use class Base { public: Base() { ... } }; and std::cout to print the message.

2

Create the Derived class inheriting from Base

Create a class called Derived that inherits from Base. Add a constructor to Derived that prints "Derived constructor called".

C++

#include 

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

// Create class Derived inheriting from Base with a constructor that prints "Derived constructor called"
// Your code here

Need a hint?

Use class Derived : public Base and add a constructor that prints the message.

3

Create a Derived object in main

In the main function, create an object called obj of type Derived.

C++

#include 

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() {
    // Create an object obj of type Derived
    // Your code here
}

Need a hint?

Inside main(), write Derived obj; to create the object.

4

Run the program and observe output

Run the program and print the output. The output should show the order in which constructors are called.

C++

#include 

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 obj;
    // Output will be shown when program runs
    // Your code here
}

Need a hint?

When you run the program, you should see the message from the Base constructor first, then the Derived constructor.