.cpp 文件中纯虚函数的正确返回值应该是多少？

Question

I am new in C++ and have a basic question. My program has a header file and a .cpp one as well. In the header file there are two functions:

int getSize() const = 0;
string getName() const = 0;

and in the corresponding part of the .cpp file:

int Class1::getSize() const { return 0;};
string Class1::getName() const {return "";};

What should I use inside the body of each function in .cpp file? As these two functions are overwritten in the derived classes, can I put anything in the body of the classes in the .cpp file? for example can I leave their bodies empty? (although I receive warning messages) or use null for string or any other values for each. I am looking for a standard and correct way of doing it. Thanks.

Answer 1

For pure virtual functions, you can omit the definition altogether. There are exceptions, when you must give a definition:

• pure virtual destructors (because destructors of derived classes will call it)
• if you call a pure virtual function (for example, from a function of a derived class)