C++基类构造器的自动调用

虽然基类的构造器和解构器不会被派生类继承，但它们会被派生类的构造器和解构器自动调用，今天我们用代码实证一下。

验证代码

源代码，仔细看注释内容：
D:\YcjWork\CppTour>vim c2004.cpp

#include <iostream>

using namespace std;
/**
 * 基类不同构造器的调用
*/
class Mother{
public:
	Mother(){
		cout << "Mother: no param" << endl;
	}
	Mother(int a){
		cout << "Mother: int param" << endl;
	}
	~Mother(){
		cout << "Deconstruction Mother" << "\n\n";
	}
};
class Daughter: public Mother{
public:
	Daughter(int a){ //派生类构造器调用基类的默认构造器Mother()
		cout << "Daughter: int param" << "\n\n";
	}
	~Daughter(){
		cout << "Deconstruction Daughter" << "\n";
	}
};
class Son: public Mother{
public:
	Son(int a): Mother(a){ //派生类构造器调用基类的指定构造器Mother(int a)
		cout << "Son: int param" << "\n\n";
	}
	~Son(){
		cout << "Deconstruction Son" << "\n";
	}
};
 
int main(){
	{
		Daughter mary(5);
	}
	{
		Son jack(6);
	}
	return 0;
}

编译运行

构造器的调用顺序：
先构造基类，再构造派生类

解构器的调用顺序：
先派生类解构，再基类解构

D:\YcjWork\CppTour>gpp c2004

D:\YcjWork\CppTour>g++ c2004.cpp -o c2004.exe

D:\YcjWork\CppTour>c2004
Mother: no param
Daughter: int param

Deconstruction Daughter
Deconstruction Mother

Mother: int param
Son: int param

Deconstruction Son
Deconstruction Mother


D:\YcjWork\CppTour>

运行截屏
C++基类构造器的自动调用