Detecting already executing applications

[FredrikE]

How can I detect whether my application already is running (or not) ?

Theres no need to start one instance for every file double-clicked in the Explorer in an MDI-app. Compare Word etc. which only launches a single window (or at least used to). /Fredrik Eriksson

 

[hennep]

Check the second option of the WinMain function:

HINSTANCE hPrevInstance

The handle of the previous instance of this application. This value is NULL if this is the first instance.

 

[FredrikE]

Since I'm running Win98 all hPrevInstance are NULL... /Fredrik Eriksson

 

[hennep]

You are right, it is always null for win32 apps.
this is straight from the cbuilder help:

hPrevInstance

Identifies the previous instance of the application. For a Win32-based application, this parameter is always NULL. If you need to detect whether another instance already exists, create a named mutex using the CreateMutex function. If the GetLastError function returns ERROR_ALREADY_EXISTS, another instance of your application exists (it created the mutex).

 

[butthead]

This checks for a a previous instance of the program running.

CreateMutex(NULL, true,
"The name of the program + ver # + name"

if (GetLastError() != ERROR_ALREADY_EXISTS)
{
Application->Run ();
}

Put this in the winmain

tomcruz.net

 

[butthead]

The string paraameter can also be created by randomly
hitting the keyboard to obtain a random string.

such as

CreateMutex(NULL, true,
"o49p324853;u; asd;e98;reu; sesdfg;dfg9875bv873p"

tomcruz.net