Which of the following operators must always be overloaded in order to be used on class objects?

Question

Which of the following operators must always be overloaded in order to be used on class objects?

 

The assignment operator =

The address operator &

The modulus operator %

The comma operator ,

 

I'm having trouble answering the question above.  Can anyone help me?

Answer 1

The address of (&) and the comma (,) operators cannot be overloaded. As was previously stated the assignment operator(=) is implicitly defined by the compiler if it hasn't been explicitly defined. The modulus operator (%) can be overloaded, but not as previously defined [N operator%(const N&, const N&);]. The prototype should be:

N operator%(const N&) const; since it is a binary operator and the value on the left of the operator is the calling instance and is implicitly passed into the function (within the function it is referenced as the "this pointer"). The const outside of the parentheses says that the value on the left of the operator will not be changed in this function. The value on the right of the operator is passed as the parameter, which also will not be changed in the function.

Answer 2

(I assume this is in regards to C++. I'm not quite sure I understood the wording of you question, but hopefully this helps.) The assignment operator= is always overloaded implicitly in a class/struct. Generally it's a good idea to explicitly overload it however, in all but the most trivial cases.