C++类继承--构造函数时先构造基类

以下说明继承类函数构造时，先构造基类；

析构基类时，若没加上virtual，只析构基类，不析构派生类；

析构派生类时，同时会析构基类；

1. 基类析构函数有virtual

#include <stdio.h>

class Base
{
public:
	int a;
	Base(){
		a=0;
		printf("base construct\n");
	}
	virtual ~Base(){
		printf("base delete\n");
	}

	virtual void setA()=0;

};

class A:public Base
{
public:
	A(){
		a = 10;
		printf("A construct\n");
	}
	~A(){
		printf("A class delete\n");
	}
	virtual void setA()
	{
		a = 2;
	}
};

int main()
{

	Base *x = new A();
	A *aClass = new A();

	delete x;
	printf("---------------\n");
	delete aClass;

	return 0;
}

运行结果：

2. 基类析构函数无virtual

class Base
{
public:
	int a;
	Base(){
		a=0;
		printf("base construct\n");
	}
	~Base(){
		printf("base delete\n");
	}
	virtual void setA()=0;
};

　　运行结果为：