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J Smith
J Smith

Reputation: 2405

what is the difference between ProcessStartInfo's UseShellExecute and CreateNoWindow?

If I were to write a console application that starts another console application as a new process, and use the default "UseShellExecute" and "CreateNoWindow" values, the result is that a new command line window appears next to the console application's window:

   UseShellExecute=true and CreateNoWindow=false

Now if I were to use the following, no new window would be created but the output of the launched process would appear on the window of the application that launched it:

   UseShellExecute=false and CreateNoWindow=false

And If I were to use the following, neither a new window would be created nor the output of the launched process appear on the window of the application that launched it:

   UseShellExecute=false and CreateNoWindow=true

But it seems that "CreateNoWindow" has no effect when UseShellExecute=true, so what role does "CreateNoWindow" play when UseShellExecute=true? Does it apply only when the application launched as a new process is a Forms application?

Upvotes: 4

Views: 2196

Answers (1)

Hans Passant
Hans Passant

Reputation: 941545

It plays no role. The rule is that CreateNoWindow will only have an effect when:

  1. You use UseShellExecute = false so that the CreateProcess() winapi is used to start the program
  2. The program you start is a console mode application.

If the app is a native Windows GUI app that creates it own window then you can ask it to not create a visible window with WindowStyle = ProcessWindowStyle.Hidden. There are however a lot of programs that ignore this request. They should, only way to stop it is through Task Manager. Next reasonable choice is ProcessWindowStyle.Minimized

Upvotes: 4

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