How does this C++ code work? Uninitialized Pointer [duplicate]

Question

Possible Duplicate:
What will happen when I call a member function on a NULL object pointer?

class A {
  public:
    void foo() { cout << "Work";}
    void bar() { this->foo(); }//new edit, works too!
};

class B {
  private:
    A *a; //never initialized
  public:
    A& getA() {
      return *a;
    }
};

void SomeFunction() {
    B *b = new B();
    B& bRef = *b;
    bRef.getA().bar();//edited
    delete b;
}

I called SomeFunction() without initializing "a" and it still prints "Work" correctly. I don't understand why, it should have bailed out with segmentation fault!

Answer 1

This is undefined behavior, but it will work on most compilers, as foo is not virtual and it doesn't use the this pointer.

Answer 2

Remember classes are just a construct of C++. When compiled, all class methods are just static methods that accept a hidden this parameter.

Given that your foo() method never references any data members, it never needs to use it, and so runs fine despite the uninitialised value of this.