Question

I want to create a simple editor like Notepad++ with simple functionality… I need to color a specific word in the rich text box area. How can I do that?

For example: when the user write these word, I want to color them to the blue color. These words are: for, while, if, try, etc.

How can I make the richtextbox to select a specific word and then color them?
And, if I want to make a comment and color everything after the //, how is that done in the richtextbox?

How do I number the line in the text box, so I can now the line number when I’m coding in my editor?

Answer 1

Here’s some code you can build on in order to achieve the functionality you want.

private void ColourRrbText(RichTextBox rtb)
{
    Regex regExp = new Regex("\b(For|Next|If|Then)\b");

    foreach (Match match in regExp.Matches(rtb.Text))
    {
        rtb.Select(match.Index, match.Length);
        rtb.SelectionColor = Color.Blue;
    }
}

The CodeProject article Enabling syntax highlighting in a RichTextBox shows how to use RegEx in a RichTextBox to perform syntax highlighting. Specifically, look at the SyntaxRichtTextBox.cs for the implementation.