空指针访问类成员函数

//空指针访问类成员函数

 1 #include<iostream>
 2 #include<string>
 3 using namespace std;
 4 
 5 class Person
 6 {
 7 public:
 8     void showinfo()
 9     {
10         cout << "空指针访问成员函数成功" << endl;
11     }
12 
13     void showinfo1()
14     {
15         cout << age << endl;
16     }
17 
18     void showinfo2()
19     {
20         cout << this->age << endl;
21     }
22 
23     void showinfo3()
24     {
25         if (this==NULL)
26         {
27             return;
28         }
29         cout << this->age << endl;
30     }
31         
32 private:
33     int age;
34 };
35 
36 int main()
37 {
38     Person *p = NULL;
39     p->showinfo();
40     //p->showinfo1();空指针报错
41     //p->showinfo2();空指针报错
42     p->showinfo3();//判断空值习惯，增强代码健壮性，不报错
43 
44     system("pause");
45     return 0;
46 }