Question

I tried to have one static const member variable to relate to another static const variable in a class.
The motivation is that if I need to modify one value later (when coding), i don’t need to change all of those that are related to each other one by one.

For example:

class Box
{
    public:
        Box();
    private:
        static const double height = 10.0;
        static const double lid_height = 0.5 + height;
};

It won’t compile and the error was ”Box::height’ cannot appear in a constant-expression’. So I guess you must type in the value of a static const member. But is there a way to have one member relate to another member variable of the same class, given that they will all be static const??

Answer 1

Set the value of your static const member variables outside of the class declaration, using the following syntax.

// box.h
#pragma once

class box
{
public:
static const float x;   
};

const float box::x = 1.0f;