Redirecting Console.WriteLine() to Textbox

Question

I'm building this application in Visual Studio 2010 using C#.

Basically there are 2 files, form1.cs (which is the windows form) and program.cs (where all the logic lies).

//form1.cs public partial class Form1 : Form {     //runButton_click function }  //program.cs class Program {     static void Main()     {         while(blah-condition)         {             //some calculation             Console.WriteLine("Progress " + percent + "% completed.");         }     } } 

There is a Run button and a blank textbox.

When the user hits the Run button, program.cs will perform some task and constantly printing out the progress using Console.WriteLine() onto the console (command prompt).

Question: How can I print to the textbox on form1 instead of printing into command prompt? I will need to print the progress constantly without any user action.

Thanks in advance!

By the way, it doesn't have to be a textbox, it can be a label or something else that can take text. I chose textbox because it makes more sense to me.

Answer 1

Start by creating a new TextWriter that is capable of writing to a textbox. It only needs to override the Write method that accepts a char, but that would be ungodly inefficient, so it's better to overwrite at least the method with a string.

public class ControlWriter : TextWriter {     private Control textbox;     public ControlWriter(Control textbox)     {         this.textbox = textbox;     }      public override void Write(char value)     {         textbox.Text += value;     }      public override void Write(string value)     {         textbox.Text += value;     }      public override Encoding Encoding     {         get { return Encoding.ASCII; }     } } 

In this case I've had it just accept a Control, which could be a Textbox, a Label, or whatever. If you want to change it to just a Label that would be fine.

Then just set the console output to a new instance of this writer, pointing to some textbox or label:

Console.SetOut(new ControlWriter(textbox1)); 

If you want the output to be written to the console as well as to the textbox we can use this class to create a writer that will write to several writers:

public class MultiTextWriter : TextWriter {     private IEnumerable<TextWriter> writers;     public MultiTextWriter(IEnumerable<TextWriter> writers)     {         this.writers = writers.ToList();     }     public MultiTextWriter(params TextWriter[] writers)     {         this.writers = writers;     }      public override void Write(char value)     {         foreach (var writer in writers)             writer.Write(value);     }      public override void Write(string value)     {         foreach (var writer in writers)             writer.Write(value);     }      public override void Flush()     {         foreach (var writer in writers)             writer.Flush();     }      public override void Close()     {         foreach (var writer in writers)             writer.Close();     }      public override Encoding Encoding     {         get { return Encoding.ASCII; }     } } 

Then using this we can do:

Console.SetOut(new MultiTextWriter(new ControlWriter(textbox1), Console.Out)); 

Answer 2

I use sth like this for a listbox:

    public class ListBoxWriter : TextWriter //this class redirects console.writeline to debug listbox {     private readonly ListBox _list;     private StringBuilder _content = new StringBuilder();      public ListBoxWriter(ListBox list)     {         _list = list;     }      public override Encoding Encoding     {         get { return Encoding.UTF8; }     }     public override void Write(char value)     {         base.Write(value);         _content.Append(value);          if (value != '\n') return;         if (_list.InvokeRequired)         {             try             {                 _list.Invoke(new MethodInvoker(() => _list.Items.Add(_content.ToString())));                 _list.Invoke(new MethodInvoker(() => _list.SelectedIndex = _list.Items.Count - 1));                 _list.Invoke(new MethodInvoker(() => _list.SelectedIndex = -1));             }             catch (ObjectDisposedException ex)             {                 Console.WriteLine(Resources.Exception_raised + " (" + ex.Message + "): " + ex);             }         }         else         {             _list.Items.Add(_content.ToString());             _list.SelectedIndex = _list.Items.Count - 1;             _list.SelectedIndex = -1;         }         _content = new StringBuilder();     } } 

and in my main application:

_writer = new ListBoxWriter(DebugWin); // DebugWin is the name og my listbox 

Console.SetOut(_writer);