MFC Dialog Based Application

Question

I have created one MFC Dialog Based application.now if i am running the application its working fine,instead of closing the application i minimized the application,if i run the application again,i am getting the Dialog.

I want to prevent the calling of application multiple times. please give me the code

Answer 1

Googling MFC Single Instance reveals http://www.codeproject.com/KB/threads/singleinstancemfc.aspx

Answer 2

The easiest way is to check in your Main() if a process of the same name as your program is already running, and quit if it is.

A google search will quickly find the relevant code, e.g. This forum post should be suitable

Answer 3

Try calling the following function in your main, before you call your application dialog class. If it returns False then then don't create your dialog and instead exit.

BOOL init()
{
   HANDLE mutex = CreateMutex(NULL, FALSE, "mutexname");
   if(mutex == NULL)
   {
      return FALSE;
   }

   if (GetLastError() == ERROR_ALREADY_EXISTS)
   { 
       /* You only need the message box if you wish to notify the user 
          that the process is running*/
       MessageBox("Another instance is already running.");
       return FALSE;
   }

   return TRUE;
}

Ensure that the mutexname is unique, use VS to generate a GUID and use that in string form as the mutex name.