C++Note 空指针访问成员函数

#include <iostream>
using namespace std;

class Person
{
public:
    void showClassName()
    {
        cout << "This is Person Class" << endl;
    }
    void showPersonAge()
    {
        cout << "Person Age = " << m_Age << endl;//m_Age默认为  this->m_Age 此时this为空 报错
    }
    int m_Age;

};
void test()
{
    Person* p = NULL;
    p->showClassName();//正常调用
    //p->showPersonAge();//报错: 原因是传入的指针为空
}
int main()
{
    test();
    system("pause");
    return 0;
}

修改showPersonAge()     增加代码的健壮性

void showPersonAge()
    {
        if (this == NULL)
        {
            return;
        }
        cout << "Person Age = " << m_Age << endl;
    }