空指针访问类成员函数

//空指针访问类成员函数

#include<iostream>
#include<string>
using namespace std;

class Person
{
public:
    void showinfo()
    {
        cout << "空指针访问成员函数成功" << endl;
    }

    void showinfo1()
    {
        cout << age << endl;
    }

    void showinfo2()
    {
        cout << this->age << endl;
    }

    void showinfo3()
    {
        if (this==NULL)
        {
            return;
        }
        cout << this->age << endl;
    }
        
private:
    int age;
};

int main()
{
    Person *p = NULL;
    p->showinfo();
    //p->showinfo1();空指针报错
    //p->showinfo2();空指针报错
    p->showinfo3();//判断空值习惯，增强代码健壮性，不报错

    system("pause");
    return 0;
}