(c + +) constructors and destructors in C + + class inheritance

Source: Internet
Author: User

Thought:

In the class inheritance of C + +,

When an object is created, the constructor of the base class is called first, and then the constructor of the next derived class is called, and so on;

When the object is reconstructed, its order is exactly the opposite of the construction;

Example:
#include <iostream>using namespace Std;class shape{public:void Draw () {cout<< "Base::D Raw ()" &LT;&LT;ENDL;}    void Erase () {cout<< "Base::erase ()" &LT;&LT;ENDL;}    Shape () {Draw ();} ~shape () {Erase ();}};/    /-------------------------------------------------class Polygon:public Shape{public:polygon () {Draw ();}    void Draw () {cout<< "Polygon::D Raw ()" &LT;&LT;ENDL;}    void Erase () {cout<< "Polygon Erase ()" &LT;&LT;ENDL;} ~polygon () {Erase ();}};/    /--------------------------------------------------class Rectangle:public Polygon{public:rectangle () {Draw ();}    void Draw () {cout<< "Rectangle::D Raw ()" &LT;&LT;ENDL;}    void Erase () {cout<< "Rectangle Erase ()" &LT;&LT;ENDL;} ~rectangle () {Erase ();}};/    /--------------------------------------------------class Square:public Rectangle{public:square () {Draw ();}    void Draw () {cout<< "Square::D Raw ()" &LT;&LT;ENDL;}    void Erase () {cout<< "Square Erase ()" &LT;&LT;ENDL;} ~square () {ErasE ();}};/    /--------------------------------------------------int main () {Polygon C;    Rectangle s;    Square T;    cout<< "------------------------------------------" <<endl; return 0;}
Results:

(c + +) constructors and destructors in C + + class inheritance

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