Diagnostics

Debug.WriteLine

Writes to the trace listeners in the Listeners collection when the application is compiled in debug configuration.

public static void Main(string[] args)
{
    Debug.WriteLine("Hello");
}

In Visual Studio or Xamarin Studio this will appear in the Application Output window. This is due to the presence of the default trace listener in the TraceListenerCollection.

Redirecting log output with TraceListeners

You can redirect the debug output to a text file by adding a TextWriterTraceListener to the Debug.Listeners collection.

public static void Main(string[] args)
{
    TextWriterTraceListener myWriter = new TextWriterTraceListener(@"debug.txt");
    Debug.Listeners.Add(myWriter);
    Debug.WriteLine("Hello");

    myWriter.Flush();
}

You can redirect the debug output to a console application’s out stream using a ConsoleTraceListener.

public static void Main(string[] args)
{
    ConsoleTraceListener myWriter = new ConsoleTraceListener();
    Debug.Listeners.Add(myWriter);
    Debug.WriteLine("Hello");
}