Common/LimitSingleInstance.h

@@ -0,0 +1,38 @@
+#ifndef LimitSingleInstance_H
+#define LimitSingleInstance_H
+
+#include <windows.h> 
+
+//this code is from Q243953 in case you lose the article and wonder
+//where this code came from...
+class CLimitSingleInstance
+{
+protected:
+	DWORD  m_dwLastError;
+	HANDLE m_hMutex;
+	
+public:
+	CLimitSingleInstance(TCHAR *strMutexName)
+	{
+		//be sure to use a name that is unique for this application otherwise
+		//two apps may think they are the same if they are using same name for
+		//3rd parm to CreateMutex
+		m_hMutex = CreateMutex(NULL, FALSE, strMutexName); //do early
+		m_dwLastError = GetLastError(); //save for use later...
+	}
+	
+	~CLimitSingleInstance() 
+	{
+		if (m_hMutex)  //don't forget to close handles...
+		{
+			CloseHandle(m_hMutex); //do as late as possible
+			m_hMutex = NULL; //good habit to be in
+		}
+	}
+	
+	BOOL IsAnotherInstanceRunning() 
+	{
+		return (ERROR_ALREADY_EXISTS == m_dwLastError);
+	}
+};
+#endif