Question

This may be a silly question about inheritance, but it does not make much sense on why I am not allowed to do this. The base class I am inheriting from is std::string:

class A : public std::string

When I use class A, I want to do this:

A text;
std::string str = "hello";
text = str;

The compiler complains that there is no binary operator = to do this.

The reason I want to inherit from string is to add some extra functionality but not lost the functionality std::string gives by default.

Is there a reason why a base class cannot be automatically assigned to a sub class?

Thanks.

Answer 1

You cannot inherit assignment operators, they are given special treatment. You can use using to bring them up from the base class.

Also, it’s horrendously bad to inherit from Standard-provided classes, except iostream.