c++中基类与派生类中隐含的this指针的分析

 1 #include<iostream>
 2 using namespace std;
 3 
 4 class Parent{
 5      public:
 6          int x;
 7          Parent *p;
 8      public:
 9          Parent(){}
10          Parent(int x){
11            this->x=x; 
12            p=this;
13         }
14          virtual void f(){
15             cout<<"Parent::f()"<<endl; 
16         }
17         void g(){
18             cout<<"Parent::g()"<<endl;
19         }
20     
21         void h(){
22             cout<<"Parent::h()"<<endl;
23             f();
24             g();
25             y();
26             cout<<"LOOK HERE: "<<x<<endl;
27         }
28         
29         private:
30             void y(){
31                 cout<<"Parent::y()"<<endl;
32             }
33 };
34 
35 class Child : public Parent{
36     public:
37         int x;
38         
39     public:
40         Child(){}
41         Child(int x) : Parent(x+5){//正确的调用父类构造函数要写在初始化型参列表中 
42             
43              //这样企图调用父类的构造函数是错误的，因为这是另外创造了一个临时对象，函数结束之后就什么都没有了！ 
44             //Parent(x+5);
45             this->x=x;
46         }
47         void f(){
48             cout<<"Child f()"<<endl;
49         }
50         void g(){
51             cout<<"Child g()"<<endl; 
52         }
53 };
54 
55 int main(){
56     //例一 
57     Child *ch=new Child();
58     ch->h(); 
59     cout<<endl;
60     //例二： 
61     ch=new Child(5);
62     ch->h();
63     cout<<endl;
64     
65     //例三： 
66     ch->p->h();
67     return 0;
68 } 

/*
Parent::h()
Child f()
Parent::g()
Parent::y()
LOOK HERE: 9306304

Parent::h()
Child f()
Parent::g()
Parent::y()
LOOK HERE: 10

Parent::h()
Child f()
Parent::g()
Parent::y()
LOOK HERE: 10
*/