Constructor and Destructor Call Order in Inheritance

Intermediate11 min read•Updated: 2026-10-22

⏳ Constructor and Destructor Call Order in Inheritance

Introduction

When working with inheritance hierarchies, the compiler follows a strict, deterministic sequence for invoking constructors and destructors.

🔄 The Golden Rule of Execution Order

1CONSTRUCTION (Top-Down):
21. Base Class Constructor
32. Derived Class Constructor
4 
5DESTRUCTION (Bottom-Up / Reverse Order):
61. Derived Class Destructor
72. Base Class Destructor

💻 Code Proof

1#include <iostream>
2 
3class LayerA {
4public:
5    LayerA()  { std::cout << "[1] LayerA Constructor\n"; }
6    ~LayerA() { std::cout << "[4] LayerA Destructor\n"; }
7};
8 
9class LayerB : public LayerA {
10public:
11    LayerB()  { std::cout << "[2] LayerB Constructor\n"; }
12    ~LayerB() { std::cout << "[3] LayerB Destructor\n"; }
13};
14 
15int main() {
16    std::cout << "--- Creating Object --- \n";
17    {
18        LayerB objectB;
19    } // objectB destroyed here
20    std::cout << "--- Object Destroyed --- \n";
21    return 0;
22}

Console Output:

1--- Creating Object --- 
2[1] LayerA Constructor
3[2] LayerB Constructor
4[3] LayerB Destructor
5[4] LayerA Destructor
6--- Object Destroyed --- 

💡 Rationale

A derived class depends on its base class foundations. Therefore, the base class must be fully constructed before derived member initializers run. When tearing down, the derived class is destroyed first so that it does not attempt to access already-destroyed base members.

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Virtual Functions, Dynamic Dispatch, and the vtable Mechanism

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Base Classes and Derived Classes (Single and Multi-Level Inheritance)	Virtual Functions, Dynamic Dispatch, and the vtable Mechanism

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Virtual Functions, Dynamic Dispatch, and the vtable Mechanism

Constructor and Destructor Call Order in Inheritance

Intermediate11 min read•Updated: 2026-10-22

Study Materials

⏳ Constructor and Destructor Call Order in Inheritance

Introduction

When working with inheritance hierarchies, the compiler follows a strict, deterministic sequence for invoking constructors and destructors.

🔄 The Golden Rule of Execution Order

1CONSTRUCTION (Top-Down):
21. Base Class Constructor
32. Derived Class Constructor
4 
5DESTRUCTION (Bottom-Up / Reverse Order):
61. Derived Class Destructor
72. Base Class Destructor

💻 Code Proof

1#include <iostream>
2 
3class LayerA {
4public:
5    LayerA()  { std::cout << "[1] LayerA Constructor\n"; }
6    ~LayerA() { std::cout << "[4] LayerA Destructor\n"; }
7};
8 
9class LayerB : public LayerA {
10public:
11    LayerB()  { std::cout << "[2] LayerB Constructor\n"; }
12    ~LayerB() { std::cout << "[3] LayerB Destructor\n"; }
13};
14 
15int main() {
16    std::cout << "--- Creating Object --- \n";
17    {
18        LayerB objectB;
19    } // objectB destroyed here
20    std::cout << "--- Object Destroyed --- \n";
21    return 0;
22}

Console Output:

1--- Creating Object --- 
2[1] LayerA Constructor
3[2] LayerB Constructor
4[3] LayerB Destructor
5[4] LayerA Destructor
6--- Object Destroyed --- 

💡 Rationale

Next Lesson

Virtual Functions, Dynamic Dispatch, and the vtable Mechanism

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Base Classes and Derived Classes (Single and Multi-Level Inheritance)	Virtual Functions, Dynamic Dispatch, and the vtable Mechanism

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next