Reference as class member initialization

Question

I want to initialize a property of a class that holds a reference to another class by passing such a reference as a parameter to the constructor. However I receive an error:

Answer 1

“'TaxSquare::bank' must be initialized in constructor base/member initializer list”. What is wrong in the following code of the classes?

What is wrong is that TaxSquare::bank is not being initialized in the constructor base/member initialization list, exactly as it says.

"The constructor base/member initialization list" is the initialization list for the constructor in question, TaxSquare::TaxSquare(int, int, Bank&). You're already using it to initialize the base (Square). You must use it to initialize the bank member, because it is of a reference type. Things not specified in the initialization list get default-initialized, and there is no default-initialization for references, because they must always reference something, and there is no default something for them to reference.

Honestly, I find that using references for data members in C++ is more trouble than it's worth, 99% of the time. You're probably better off with a smart pointer, or even a raw one. But you should still initialize that with the initialization list, even if you could get away without. Same goes for the taxAmount, really.

// TaxSquare::TaxSquare(int anID, int amount, Bank& theBank) : Square(anID)
// That thing after the colon is the initialization list:      ^^^^^^^^^^^^
// So add the other members to it, and then notice that there is nothing left
// for the constructor body to do:
TaxSquare::TaxSquare(int anID, int amount, Bank& theBank) : 
Square(anID), taxAmount(amount), bank(theBank) {}