How to initial static member in C++ using function

Question

I am using C++.

in .h:

static CRITICAL_SECTION g_CS;

in .cpp:

CRITICAL_SECTION CQCommon::g_CS;

but I want to use

QGUID temp;
EnterCriticalSection(&g_CS);
temp = g_GUID++;
LeaveCriticalSection(&g_CS);
return temp;

in one static function. How can I invoke InitializeCriticalSection(PCRITICAL_SECTION pcs);?

Can I using the following one:

QGUID func(XXX)
{
    static {
    InitializeCriticalSection(&g_CS);
    }
                    QGUID temp;
                    EnterCriticalSection(&g_CS);
                    temp = g_GUID++;
                    LeaveCriticalSection(&g_CS);
                    return temp;
}

And how can I invoke DeleteCriticalSection(&g_CS) after app leave?

Using MFC, it seems CCriticalSection is a solution.

Answer 1

If you want a different approach you can create an object to manage it:

class CriticalSectionManager
{
  public:
  CriticalSectionManager()
  {
    InitializeCriticalSection(&g_CS);
  }
  ~CriticalSectionManager()
  {
     DeleteCriticalSection(&g_CS);
  }
};

void Func(void)
{
  static CriticalSectionManager man;
  //Do stuff
}

This will now be managed automatically by C++. The critical section will be initialized when the function is first entered, and deleted when the program exits.

Furthermore you can extend this by having the actual PCRITICAL_SECTION variable inside the class, etc.. etc..

Answer 2

In the entry point to your code - the main function, call the init:

int main(...)
{
  InitializeCriticalSection(&g_CS);

  // do some stuff

  DeleteCriticalSection(&g_CS);

  // exit
  return 0;
}

Answer 3

Well, today the best practice is to use "scoped lock" pattern instead of EnterXXX and LeaveXX -like functions. Take a look at what boos has to offer. Regardless, an RAII approach can help you here:

class MyCriticalSection
{
private: 
    CRITICAL_SECTION m_CS;
public:
    MyCriticalSection()
   {
     ::InitializeCriticalSection(&m_CS);
    }
   ~MyCriticalSection()
   {
     ::DeleteCriticalSection(&m_CS);
   }
   void Lock()
   {
     ::EnterCriticalSection(&m_CS);
   }
   void UnLock()
   {
     ::LeaveCriticalSetion(&m_CS);
   }
}