.NET - WindowStyle = hidden vs. CreateNoWindow = true?

Question

When I start a new process, what difference does it make if I use the

WindowStyle = Hidden

or the

CreateNoWindow = true

property of the ProcessStartInfo class?

Answer 1

As Hans said, WindowStyle is a recommendation passed to the process, the application can choose to ignore it.

CreateNoWindow controls how the console works for the child process, but it doesn't work alone.

CreateNoWindow works in conjunction with UseShellExecute as follows:

To run the process without any window:

ProcessStartInfo info = new ProcessStartInfo(fileName, arg); 
info.CreateNoWindow = true; 
info.UseShellExecute = false;
Process processChild = Process.Start(info); 

To run the child process in its own window (new console)

ProcessStartInfo info = new ProcessStartInfo(fileName, arg); 
info.UseShellExecute = true; // which is the default value.
Process processChild = Process.Start(info); // separate window

To run the child process in the parent's console window

ProcessStartInfo info = new ProcessStartInfo(fileName, arg); 
info.UseShellExecute = false; // causes consoles to share window 
Process processChild = Process.Start(info);