Issue with opening mulitple instance of same application

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I have an VC++ 6.0 application.What I need is if application is already running and again If I run another instance of same application I want the previous instance to be opend

Posted 1-Jun-11 2:14am

SandhyaMadhu

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3 solutions

Solution 2

one quick solution is that create a mutext in your applications InitInstance() function. refer http://www.codeguru.com/forum/showthread.php?t=312467[^]
after this within
case ERROR_ALREADY_EXISTS:
call the function FindWindow() by passing the window name.
u get the handle to the window.
then send the message to show the window by calling the function SendMessage() with proper parameters to maximize the window. You can somehow maximize the window since you have the handle.

Not sure whether its a good solution.

Posted 1-Jun-11 2:39am

Resmi Anna

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వేంకటనారాయణ(venkatmakam) · Accepted Answer · 2011-06-01T02:40:00

First create a unique mutex (with some guid)in your InitInstance() method.Then check GetLastError value.if you get the error saying mutex already exist then use FindWindow API with your class name and your window name to window the existing window handle.The use ShowWindow API with that handle,and return from it.
Bored of explanation then look this algorithm,

C#

::CreateMutex(NULL, false, TEXT("UniqueMutexName"));
if (::GetLastError() == ERROR_ALREADY_EXISTS)
{
    HWND hMyPrevWnd = ::FindWindow(YourClass, YourWindoName); //Check Msdn for more info
    if(hMyPrevWnd != NULL)
    {
        ::ShowWindow(hMyPrevWnd, SW_SHOW);
    }
}

barneyman · Accepted Answer · 2011-06-01T02:23:00

Solution 1

Search CodeProject for 'only open one instance'[^]

Choose Articles, Tech Blogs and Tips and Tricks

Be aware, if you try the mutex approach, you need to test behaviour with concurrent windows stations, concurrent logins (on a server, for instance) and and Terminal Services/mstsc (similar problems to windows stations)

Posted 1-Jun-11 2:23am

barneyman

Updated 1-Jun-11 15:16pm

v2

Comments

Albert Holguin 1-Jun-11 21:04pm

um... your search doesn't bring up anything relevant unless you select "Everything"... that's probably why you're getting the downvotes... you should consider revising your post... I'll upvote you if you come up with a better search query! :)

barneyman 1-Jun-11 21:14pm

granted - i think the point i was trying to make was that there were a myriad of solutions already on here for that common problem

Albert Holguin 1-Jun-11 21:15pm

I know... I didn't downvote you! ..I knew what you were going for! :D