组合类的构造函数的调用顺序

心已赠人 2023-10-11 10:33 20阅读 0赞

文章来源:https://bbs.csdn.net/topics/390253882
    
    “构造函数调用顺序：先调用内嵌对象的构造函数（按内嵌时的声明顺序，先声明者先构造）。然后调用本类的构造函数。（析构函数的调用顺序相反）”
    
    #include<iostream>
    using namespace std;
    class Part //部件类
    {
    public:
        Part() {cout<<"Part default construction called"<<endl;}
        Part(int i) {cout<<"Part: "<<i<<" construction called"<<endl;} 
        ~Part() {cout<<"Part deconstruction called"<<endl;}
    private:
        int val;
    };
     
    class Whole
    {
    public:
        Whole();
        Whole(int i,int j,int k);
        ~Whole();
    private:
            //这三个变量的声明顺序改变，打印输出的结果仍然一样
        Part one;    
        Part two;
        int  date;
    };
     
    Whole::Whole()
    {    date=0;}
    Whole::Whole(int i,int j,int k)
    :one(j),date(k),two(i)    //这里的初始化顺序按照one(2),date(3),two(1)进行,按照i,j,k的顺序来的.
    :/*one(j),*/date(k), two(i)   //默认构造one 
    { cout<<"Whole's construction called!"<<endl; }
     
    Whole::~Whole()
    {
        cout<<"Whole deconstruction called!"<<endl; 
    }
    int main(void)
    {
        Whole w(1, 2, 3);
        return 1;
    }

输出结果:

Part: 2 construction called  
Part: 1 construction called  
Whole's construction called!

Whole deconstruction called!  
Part deconstruction called  
Part deconstruction called

“构造函数调用顺序：先调用内嵌对象的构造函数（按内嵌时的声明顺序，先声明者先构造,比如上面的按照i,j,k）。然后调用本类的构造函数。（析构函数的调用顺序相反）”

转载于:https://www.cnblogs.com/Stephen-Qin/p/11512427.html