overriding

Consider the following piece of code: class foo { private function m() { echo 'foo->m() '; } public function call() { $this->m(); } } class bar extends foo { private function m() { echo 'bar->m() '; } public function callbar() { $this->m(); } } $bar = new bar; $bar->call(); $bar->callbar(); Now, changing the visibility of the m() method, I get: ( + for public , - for private ) Visibility bar->call() bar->callbar() ====================================================== -foo->m(), -bar->m() foo->m() bar->m() -foo->m(), +bar->m() foo->m() bar->m() +foo->m(), -bar->m() ERROR ERROR +foo->m(), +bar-

What is the purpose of using the reserved word virtual in front of functions? If I want a child class to override a parent function, I just declare the same function such as void draw(){} . class Parent { public: void say() { std::cout << "1"; } }; class Child : public Parent { public: void say() { std::cout << "2"; } }; int main() { Child* a = new Child(); a->say(); return 0; } The output is 2. So again, why would the reserved word virtual be necessary in the header of say() ? Thanks a bunch. krolth This is the classic question of how polymorphism works I think. The main idea is that you want

public class NaiveAlien extends Alien { @Override public void harvest(){} } I was trying to understand my friend's code, and I do not get the syntax, @Override in the code. What does that do and why do we need in coding? Thanks. It's a hint for the compiler to let it know that you're overriding the method of a parent class (or interface in Java 6). If the compiler detects that there IS no function to override, it will warn you (or error). This is extremely useful to quickly identify typos or API changes. Say you're trying to override your parent class' method harvest() but spell it harvset() ,

Yes, I do understand the difference between them. What I want to know is: why OVERRIDE a method? What is the good in doing it? In case of overload: the only advantage is you haven't to think in different names to functions? Overloading generally means that you have two or more functions in the same scope having the same name. The function that better matches the arguments when a call is made wins and is called. Important to note, as opposed to calling a virtual function, is that the function that's called is selected at compile time. It all depends on the static type of the argument. If you