Why can I call a non-statistical member function without an object instance?

Question

Possible duplicate:
What happens when I call a member function on a NULL object pointer?

Well, I think this code and program output explains itself:

#include <iostream> #include <string> using namespace std; class Test { public: void Not_Static(string args) { cout << args << endl; } }; int main() { Test* Not_An_instance = nullptr; Not_An_instance->Not_Static("Non-static function called with no object?"); cin.ignore(); return 0; } 

program output:

A non-static function called without an object?

Why is this possible?

Answer 1

Undefined. Your program invokes undefined behavior by calling a method with a null pointer, so it is allowed , including your output.

Remember: the C ++ language specification does not indicate the output of each possible program to leave room for optimization. Many things are not explicitly tested and can lead to behavior that seems wrong or illogical, but just vague.

Answer 2

This behavior is undefined - so it is entirely possible that it will print this output. The problem is that undefined behavior can bite you, so you should not do this.

Answer 3

Because it does not use this and therefore does not look for a null pointer. Make it virtual, and it most likely will fail.