How to Undo and Redo in C# (Rich Text Box)

Question

I\'ve been trying to get undo and redo working in my text editor for about 3 days now. It\'s doing my head in.

I have a text box (n

Answer 1

You can have the RichTextBox build the undo stack for you word by word, plus keep track of the caret position, by handling one of the KeyDown-, KeyPress- or KeyUp events like this:

 private void rtb_KeyDown(object sender, KeyEventArgs e)
    {
        // Trick to build undo stack word by word
        RichTextBox rtb = (RichTextBox)sender;
        if (e.KeyCode == Keys.Space)
        {
            this.SuspendLayout();
            rtb.Undo();
            rtb.Redo();
            this.ResumeLayout();
        }
        // eztnap
    }

Since the RichTextBox does the job for you, you just have to call rtb.Undo() or rtb.Redo() from wherever you need to.