Accessing static member variables

[saetrum]

I have base class that has a protected static member variable.

I'd like to access that variable from a non static function from within a class that inherits the base class. How would I do that?

for example:

class State
{
public
...
protected:
static SceneManager * gSM;
...
}

class GameState : public State
{
public:
void function();
...
}

void GameState ::function()
{
State::gSM->doSomething();
}


This gives me linking errors - unresolved symbol. So any ideas?

[epopov]

Your code is fine (regarding the static variable access): linker errors mean you have probably forgotten to add some .cpp files in your project. You will have to paste the full error so we can narrow the problem down.

[saetrum]

I neglected to declare the variables before I initialized them. I didn't realize that I had to actually declare the static variables at file scope before using a static function to initialize - i.e.

Code: Select all

class State 
{ 
public 
... 
protected: 
static SceneManager * gSM; 
... 
} ;
//**********FORGOT this line below**********
SceneManager * State::gSM = NULL;

class GameState : public State 
{ 
public: 
void function(); 
... 
} 

void GameState ::function() 
{ 
State::gSM->doSomething(); 
} 

[UT2007]

Code: Select all

class State 
{ 
public 
... 
protected: 
static SceneManager * gSM; 
... 
} ;
//**********FORGOT this line below**********
SceneManager * State::gSM = NULL;

class GameState : public State 
{ 
public: 
void function(); 
... 
} 

void GameState ::function() 
{ 
State::gSM->doSomething(); 
} 

This piece of code helped me to solve an important issue, i give you KUDO for this ! (idea to have NULL for scenemanager was not so evident in the fire of action)