Detailed explanation of C++ function inheritance: What should you pay attention to when using constructors and destructors in inheritance?

In C inheritance, constructor inheritance requires the first statement of the derived class constructor to call the base class constructor, and destructor inheritance requires the derived class destructor to first execute the derived class code and then call the base class destructor. Pay attention to avoid cyclic calls to constructors and destructors, ensure that the parent class constructor and destructor are implemented correctly, and use the base class pointer to call the parent class destructor.

C Detailed explanation of function inheritance: Precautions for using constructors and destructors in inheritance

In C, when a derived class inherits a base class, The behavior of derived class constructors and destructors is affected. This article will discuss in detail the considerations when using constructors and destructors in inheritance, and illustrate it through a practical case.

Constructor inheritance

When a derived class inherits from a base class, the constructor of the derived class calls the constructor of the base class to initialize the member variables of the base class. At this time, you need to pay attention to the following matters:

• The first statement in the derived class constructor must be to call the base class constructor.
• If the base class constructor is not explicitly called, the compiler will automatically call the default constructor.
• There can be multiple constructors in a derived class, but each constructor must begin with a call to the base class constructor.

Destructor inheritance

The destructor of the derived class will perform the following operations:

• Call the destructor code in the derived class destructor .
• Call the base class destructor.
• If a derived class owns a base class pointer, it should be released in the derived class destructor.

Practical Case

Consider the following code, which demonstrates the behavior of constructors and destructors in inheritance:

#include <iostream>

using namespace std;

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

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

int main() {
    Derived d;
    return 0;
}

Running this code will print the following output:

Base constructor called.
Derived constructor called.
Derived destructor called.
Base destructor called.

Notes

When using constructors and destructors in inheritance, you also need to pay attention to the following matters:

• Avoid circular calls to constructors and destructors function.
• Ensure that the constructor and destructor of the parent class are implemented correctly to avoid resource leaks or segfaults.
• When calling the parent class destructor in the derived class destructor, you should use the base class pointer instead of the derived class pointer.

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