Having single instance application

[inbugable]

Hello guys,

I have a Winforms application written in managed C++. I would like to only have one instance of my application running on a given system at a time. The reason being opening another instance of my form can really mess up the environment I'm working in.

Here's what I'm using -

public ref class CSingleInstance
{
private:
//our Mutex member variable
Mutex ^m_mutex;

public:
CSingleInstance(String ^mutexname)
{
m_mutex = gcnew Mutex(false, mutexname);
}
~CSingleInstance()
{
//release it when the CSingleInstance object is destroyed
m_mutex->ReleaseMutex ();
}
bool IsRunning()
{

return !m_mutex->WaitOne(5, true);
}
};

And in my main() -

//create a mutex with a unique name
CSingleInstance ^si= gcnew CSingleInstance("{94374E65-7166-4fde-ABBD-4E943E70E8E8}");

if(si->IsRunning())
MessageBox::Show("App already running!!");
else
// Create the main window and run it
Application::Run(gcnew Form1("NULL", "NULL"));

But the problem I'm running into is that, this only works on my laptop. When i install my application on another system, it doesnt work.

Can anybody help please??

[humptydumpty]

Please use Code tag First.Second thing Simply use CreateMutex() Function .The
CreateMutex function creates or opens a named or unnamed mutex object.If the function succeeds, the return value is a handle to the mutex object. If the named mutex object existed before the function call, the function returns a handle to the existing object and GetLastError returns ERROR_ALREADY_EXISTS. Otherwise, the caller created the mutex.

If the function fails, the return value is NULL. To get extended error information, call GetLastError.

for More Detail have a look in MSDN

Thanx

[dwurity]

Here is the code sample..

       HANDLE hndle = CreateMutex(NULL,FALSE,"TestMutex");

       if(GetLastError() != ERROR_ALREADY_EXISTS)
      {	
	//..Do your task
      }
      else
      {
                //..One Instance is already running
                return;
      }

[cilu]

[ redirected ]

[cilu]

People we are talking here about a managed application, not Win32 API.

Well, this runs ok on my PC. At the first running, exists is true, at the second (if started in less than 5 seconds) is false, just as expected.

using namespace System;
using namespace System::Threading;

int main(array<System::String ^> ^args)
{
	Mutex^ m = gcnew Mutex( false,"MyMutex" );

	bool exists = m->WaitOne(10, true);

	Console::WriteLine("Application already running {0}", exists);

	Thread::Sleep(5000);

    return 0;
}

[inbugable]

I figured out that there is one important thing we need to add -

GC::KeepAlive(mutex) to keep a hold of the mutex as long as the program is running. Now it works perfect.