I agree that returning the same type, if possible, is better, since you can model it so that one specific value (zero, empty string, etc.) expresses the "nothin

I agree that returning the same type, if possible, is better, since you can model it so that one specific value (zero, empty string, etc.) expresses the "nothing" accordingly. But I have found that several other developers don't share this view and prefer functions to return false, null, etc. instead of a value in the same space as the normal return type.