C / C++ / MFC

#include <io.h>

if (_access(dir, 0)==0)
 then it exists

BOOL CCommonFunctions::DirectoryExists(CString strPath)
{
	CFileFind finder;
	
	// check to see if path given has end slash, if not add it
	if (strPath.Right(1) != "\\") 
		strPath += _T("\\");

	strPath += _T("*."); // searching for *. returns only directories

	// start working for folders
	BOOL bWorking = finder.FindFile(strPath);
	if (!bWorking)
		return FALSE;

	finder.Close();
	return TRUE;
}

if (!CCommonFunctions::DirectoryExists("C:\\Temp\\")
AfxMessageBox("ERROR!");

BOOL CCommonFunctions::FileExists(CString strFilename)
{
	CFileFind ff;
	BOOL result = ff.FindFile(strFilename);
	if (!result) // file doesn't exist
		return false;
	
	ff.Close();
	return true;
}

if (!CComonFunctions::FileExists("C:\\test.txt")
AfxMessageBox("ERROR!");

CCriticalSection cs; // this object must be global of static in your class

// then in the function that access the CList
void CMyClass::FunctionThatAccessTheCList ()
{
  // lock this section, begins the synchronized section
  cs.Lock ();
  //.... modify the list here

  cs.Unlock ();
  // end synchronized section
}