How to detect open instance of excel from c#

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Hi I have a c# program, I need to connect to and use an instance of excel from within the program. My code is:

C#

Microsoft.Office.Interop.Excel.Application exApp = null;
try
{
  exApp = (Microsoft.Office.Interop.Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
}
catch (Exception err)
{
   MessageBox.Show("no excel running, starting new one");
}
if (!exApp.Visible)
{
   exApp = new Microsoft.Office.Interop.Excel.Application();
}

I start excel, then start the c# program, and the catch part of the try/catch block executes. My program then starts a new instance of excel. So now I have 2 instances of excel running, the one that I started maually, and the one started by my program. When I trigger this code again, the c# program finds the instance of excel that it started, and I don't see the "no excel running..." message. It seems that the call to getactiveobject only works if my program started the instance of excel... help! I want my program to find any instance of excel, not just the one that it started... (kind of new to c#, .net, ...) THanks!

Posted 13-May-14 9:46am

Member 10816215

Updated 18-Feb-16 9:17am

Nelek

v2

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Maciej Los · Answer 1 · 2014-05-13T10:26:00

Solution 1

Try Marshal.GetActiveObject[^] method as is described here: Launching Office Apps Programmatically[^]

Posted 13-May-14 10:26am

Maciej Los

Comments

Member 10816215 13-May-14 17:00pm

Thanks for your response. As you can see in my code snippet, I am using Marshal.GetActiveObject. It isn't working, I get an unhandled exception of type ....

Maciej Los 14-May-14 11:54am

Isn't working is not informative at all! If you get unhandled exception, it means there is no active Excel application ;)
Follow the link and find out how to handle it ;)

Maciej Los 14-May-14 11:57am

BTW: Why do you create another instance of Excel, if it isn't visible?

if (!exApp.Visible)
{
   exApp = new Microsoft.Office.Interop.Excel.Application();
}

CHill60 · Answer 2 · 2014-05-13T10:29:00

Have a look at this CodeProject article Finding and Listing Processes in C#[^]

On a similar question previously King_Fisher[^] also suggested this link http://stackoverflow.com/questions/4722198/checking-if-windows-application-is-running[^]. If this last link works for you then King_Fishers solution is here[^]