C++ class inheritance variables

Question

I'm working on a game, and I want to store the character belongs to a unit inside the class that defines the units. (as objects)

This is the defining class. (I use inheritance)

class Units { public: char indicator; Units(); virtual ~Units(); protected: private: }; Units::Units (){} Units::~Units (){} class WoodenBoxClass: public Units { public: WoodenBoxClass.indicator = 'B'; };

During the compilation, when "WoodenBoxClass.indicator = 'B';" comes, I get an error message:

50|error: expected unqualified-id before '.' token

What should I do? The main question is that how can I reach that the "indicator" variable is the same to every "WoodenBoxClass" object?

there is no need to define empty constructor or destructor in c++. — Elazar
– Elazar, Commented Apr 25, 2013 at 14:26

Some programmer dude · Accepted Answer · 2013-04-25 14:29:31Z

You need to initialize member variables in the class constructor. There are two ways to do it:

Simply assign to it in the child-class constructor
```
WoodenBoxClass() { indicator = 'B'; } 
```

Have a constructor in the base class that takes the indicator as argument, and use an initializer list in the child-class constructor:

class Unit { ... explicit Unit(char ind) : indicator(ind) {} ... }; class WoodenBoxClass : public Unit { ... WoodenBoxClass() : Unit('B') {} ... };

The first version works. Thank you very much, especially for the quick answer! =)

skyfree · Accepted Answer · 2013-04-25 14:30:57Z

To keep the "indicator" variable same to every "WoodenBoxClass" object, you can use static variable.

class WoodenBoxClass: public Units { public: static char indicator = 'B'; }; class Units { public: //char indicator; //not necessary actually Units(); virtual ~Units(); protected: private: };

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