Question

After importing a text file into my Windows Form Application Rich Text box, I now want to add the search function. Is it possible to have multiple SelectionStart values? The SelectionLength will be the same seeing that its the same word.

        string textfield = TextField.Text;
        string searchword = searchbox.Text;
        int found=0;
        TextField.SelectionLength = searchword.Length;
        TextField.SelectionBackColor = Color.LightBlue;

        for (int y = 0; y < textfield.Length; y++)//Goes through whole string
        {
            if (searchword[0] == textfield[y])//Looks for first character
            {
                for (int x = 0; x < searchword.Length; x++)//Checks if rest of  characters match
                {
                    if (searchword[x] == textfield[y + x])
                    {
                        found++;
                    }
                    else
                        break;
                }
            }

            if (found == searchword.Length)
            {
                TextField.SelectionStart = y;//////Want to have multiple of these
            }
            found=0;
        }
        TextField.Focus();

Answer 1

No you can’t. But you can change the back color of a selected text, for example. Start by selecting a word. Then do this

foreach (Match match in matches) {
    richTextBox.SelectionStart = match.Index;
    richTextBox.SelectionLength = match.Length;
    richTextBox.SelectionBackColor = Colors.Yellow;
}

To clear the all the markings, just select the whole text and set the back color to white (assuming that you are not using back colors otherwise).

In the example I am assuming that you are using Regex. You would find the words with:

string pattern = String.Format(@"\b{0}\b", Regex.Escape(wordToFind));
MatchCollection matches = Regex.Matches(richTextBox.Text, pattern);