How to check a Window already opened when button is clicked?

Question

I am Working in Visual Studio 2008 Winforms Application project in Windows 7 (32 bit).I am doing the project in C#. I have placed some buttons in a tab and added actions for that once it is clicked. While clicking the button am just running a .exe file in its action part. My problem is that, i opened a window by clicking one button(so the .exe file is running), now while am clicking the button again it is opening same window again irrespective of checking that it is open or not. I want to solve this issue,as when a window is opened it must not open again on another click on same button. How to solve this issue. ? Please help.... Thanks in advance..

Answer 1

You could check if the process is already running, when re-clicking the button:

private void btnStartExecutable_Click(object sender, EventArgs e)
{
   Process[] processName = Process.GetProcessesByName("InsertProcessNameHere");
   if (pname.Length == 0)
   {
       MessageBox.Show("Application isn't running yet.");
       //Start application here
       Process.Start("InsertProcessNameHere");
   }
   else
   {
       MessageBox.Show("Application is already running.");
       //Don't start application, since it has been started already
   }
}

Answer 2

The right answer here IMHO is that unless the two application shares a common resource or can talk to each other through some channel, there is no safe and efficient way to achieve what you want. Since the process is external, it could already be running before your calling app starts, or even while it's already running. You won't be able to tell if the process has been started from your app or not.

By the time I'm writing this your question does not yet state if you are in liberty to modify the external app you are calling. If you are however, using a Mutex would be a quick and easy way to solve your problem.

In your external app, whenever you want to make the other app aware of whatever condition you want (be it that the process is running or that a specific window is opened), have a Mutex instance created like this:

var mutex = new Threading.Mutex(true, "mutex unique identifier");

And in your calling app, try to create a Mutex instance with the same identifier:

bool alreadyExists;
var mutex = new Threading.Mutex(false, "mutex unique identifier", out alreadyExists);

Here the alreadyExists variable will tell you whether or not the external process is running or not. This is much safer than trying to identify it via its name, as other processes could have the same or a new version could be of a different name. Of course, the mutex identifier must be as unique as possible (like a Guid), otherwise you may encounter the same problem. ;)

Whenever you feel like the mutex must be released (at external app level), release it:

mutex.ReleaseMutex();

Note that if the process ends the mutex will be automatically released by the OS.

If the external app isn't a .NET based app, you can still create a mutex with Win32 API functions.

Answer 3

You can try this:

    bool processExited = true;
    private void button1_Click(object sender, EventArgs e)
    {
        if (processExited)
        {

            Process process = new Process();
            process.EnableRaisingEvents = true;
            process.Exited += MyProcessExited;
            process.StartInfo = new ProcessStartInfo();
            process.StartInfo.FileName = "notepad.exe";
            process.Start();
            processExited = false;
        }
        else
        {
            MessageBox.Show("Still running");
        }

    }

    void MyProcessExited(object sender, EventArgs e)
    {
        processExited = true;
    }

Answer 4

Thanks for the support.. I got the answer like this..

1) Creating an event'Exit' for the process in function button click 2) Define a function for the exit event where you set a flag 3) Check the flag is set or not everytime while opening the process in the function button click

Event for Exit: 'P' is the name of process: p.Exited += new EventHandler(p_Exited);

p_Exited will be the function name where we will set the flag.

Thanks all...

Answer 5

If you know the name of the process that gets started or the path the .exe is run from you can use the Process class to check to see if it is currently running. http://msdn.microsoft.com/en-us/library/system.diagnostics.process(v=vs.110).aspx