[c++]衍生类的构造和析构

[c++]派生类的构造和析构

#include<iostream>
using namespace std;
class Base
{
    float x;
    float y;
public:
    Base(float a,float b)
    {
        x = a;
        y = b;
        cout<<"基类构造函数被调用"<<endl;
    }
    ~Base()
    {
        cout<<"基类析构函数被调用"<<endl;
    }
    void print()
    {
        cout<<"x = "<<x<<endl;
        cout<<"y = "<<y<<endl;
    }
};
class Derived:public Base
{
    float z;
    float q;
public:
    Derived(float a,float b,float c,float d):Base(a,b)//以默认参数列表的形式把基类的私有成员赋初值
    {
        z = c;
        q = d;
        cout<<"子类构造函数被调用"<<endl;
    }
    ~Derived()
    {cout<<"子类析构函数被调用"<<endl;}
    void print()
    {
        Base::print();//调用基类的普通函数要加作用域哦
        cout<<"z = "<<z<<endl;
        cout<<"q = "<<q<<endl;
    }
};
int main()
{
    Derived b1(11.2,22.3,44.5,6.5);
    b1.print();
    return 0;
}

注意：构造函数和析构函数的调用顺序相反