multinst.c

来自「一本已经绝版的好书」· C语言 代码 · 共 68 行

/************************************************************
Module name: MultInst.C
Notices: Copyright (c) 1995-1997 Jeffrey Richter
************************************************************/


#include "..\CmnHdr.H"                  /* See Appendix C. */
#include <windows.h>
#include <tchar.h>
#include "Resource.H"


/////////////////////////////////////////////////////////////


// We instruct the compiler to put the g_lUsageCount data
// variable in its own data section called Shared. We
// then instruct the linker that we want the data in this
// section to be shared by all instances of this application.
#pragma data_seg("Shared")
LONG g_lUsageCount = -1;
#pragma data_seg()

// Instruct the linker to make the Shared section 
// readable, writable, and shared.
#pragma comment(linker, "/section:Shared,rws")


/////////////////////////////////////////////////////////////


int WINAPI _tWinMain (HINSTANCE hinstExe,
   HINSTANCE hinstPrev, LPTSTR pszCmdLine, int nCmdShow) {

   // An instance is running; increment the counter.
   BOOL fFirstInstance = 
      (InterlockedIncrement(&g_lUsageCount) == 0);

   chWARNIFUNICODEUNDERWIN95();

   // If more than one instance is running, tell
   // the user and terminate the program.
   if (!fFirstInstance) {
      MessageBox(NULL,
         __TEXT("Application is already running - ")
         __TEXT("Terminating this instance."),
         __TEXT("Multiple Instance"),
            MB_OK | MB_ICONINFORMATION);
   } else {

      // We are the only instance running; 
      // wait for the user to terminate us.
      MessageBox(NULL,
         __TEXT("Running first instance of application.\n")
         __TEXT("Select OK to terminate."),
         __TEXT("Multiple Instance"), 
         MB_OK | MB_ICONINFORMATION);
   }

   // We are no longer running; decrement the usage counter.
   InterlockedDecrement(&g_lUsageCount);

   return(0);
}


//////////////////////// End Of File ////////////////////////