Highlight all searched words

Question

In my RichtextBox, if I have written as below.

This is my pen,
his pen is beautiful.

Now I search word \"is\"

Answer 1

If you only want to match the whole word you can use this, note that this ignores case and also the |s\b means that plurals get highlighted e.g. Cat matches cats but not caterpiller :

    public static void HighlightText(RichTextBox myRtb, string word, Color color)
    {
        if (word == string.Empty)
            return;
        var reg = new Regex(@"\b" + word + @"(\b|s\b)",RegexOptions.IgnoreCase);

        foreach (Match match in reg.Matches(myRtb.Text))
        {
            myRtb.Select(match.Index, match.Length);
            myRtb.SelectionColor = color;
        }

        myRtb.SelectionLength = 0;
        myRtb.SelectionColor = Color.Black;
    }