Is a return statement mandatory for C++ functions that do not return void?

Question

My Herb Schildt book on C++ says: \"... In C++, if a function is declared as returning a value, it must return a value.\" However, if I write a function wit

Answer 1

It's not mandatory to have a return statement in a function declared as returning non-void and it doesn't have to lead to undefined behaviour.

Such a function could:

• Not return, say by entering an infinite loop
• Return by throwing an exception
• Call a function that itself does not return, such as std::terminate

Of course, if a function avoids undefined behaviour by always doing one of the above it probably shouldn't be declared as returning non-void if possible.

One obvious case where it would need to is if it is a virtual function which for a particular point in a class hierarchy can't return a valid value and always exits via an exception.