I want one application instance only

How can I prevent from opening more than one instance of my application? e.g. I want that when the user clicks on the exe file for the 2nd time then the program quits immediately.

in the main(), do a wrap on the Application.Run(new yourapp);


Process[] p = Process.GetProcessByName("youApp");
if (p.Length == 1) Application.Run(new yourapp);

Thank you very much! I could replace that Homer Simpson with you in my factory!
But mind the spelling:

Code:

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Process[] p = Process.GetProcessesByName("youApp");
if (p.Length == 1)
  Application.Run(new yourapp);

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