C++ 单实例运行

//MFC program  ：

#include <windows.h>
#pragma data_seg("Shared")     
HWND hwnd=NULL;
#pragma data_seg()
#pragma comment(linker,"/section:Shared,RWS")

	if(hwnd==NULL)
	{
		hwnd=m_hWnd;
	}else
	{
		::SetForegroundWindow(hwnd);
		ExitProcess(0);
	}

//console  program: create a section

#include <windows.h>

#pragma  data_seg("Shared")
int volatile g_lAppInstance =0;
#pragma  data_seg()


#pragma comment(linker,"/section:Shared,RWS")


if(++g_lAppInstance>1)
	{
		MessageBox(NULL,"该程序已经有一实例运行!",NULL,NULL);
		ExitProcess(0);
	}

//Mutex program:

HANDLE hObject = CreateMutex(NULL,FALSE,"LengFeng");


	if(GetLastError() == ERROR_ALREADY_EXISTS)
	{
		CloseHandle(hObject);
		MessageBox(NULL,"程序已经运行!",NULL,NULL);
		return FALSE;
	}