[C++]空的对象指针可以调用成员函数

include

using namespace std;
class A{
public:
void func()
{
cout << "hahaha" << endl;
}
int m_num = 1;
};

int main()
{
A* ptr = NULL;
A obj;
obj.func();
cout<<obj.m_num<<endl;
ptr->func();
cout<