Method resolution order in C++

Question

Consider the following class hierarchy:

• base class Object with a virtual method foo()
• an arbitrary hierarchy with multiple inheritance (virtual and non-virtual); each class is a subtype of Object; some of them override foo(), some don't
• a class X from this hierarchy, not overriding foo()

How to determine which method will be executed upon a call of foo() on an object of class X in C++?

(I'm looking for the algorithm, not any specific case.)

Answer 1

If you are talking about G++ a vtable (Virtual Method Table) is used, you can get more specific details here. Not sure if every C++ compiler uses the same approach but I would say yes

Answer 2

Some detailed description with code.

vtable and vptr

vtable

Virtual Functions

Answer 3

If a method of a base class is virtual, every call to it through base or derived pointer/reference will call the appropriate method (The one furthest down the inheritance tree). If the method was declared virtual, you can't have it any other way later : declaring it virtual (or not) in derived classes won't change anything.