Question

I’m making a small tool. The code below fires when the large RichTextBox is updated.

How can I modify this code to highlight #703919 in Color.ForestGreen, not only #?

I’d like to keep the code as concise as possible.

private void CSS_TextChanged(object sender, EventArgs e)
{
    CSS.Select(0, CSS.TextLength);
    CSS.SelectionColor = CSS.ForeColor;

    string[] Keywords = {"background", "filter", ":", "#"};
    Color[] Colours = {Color.DarkBlue, Color.DarkBlue, Color.Magenta, Color.ForestGreen};

    for(int i = 0; i < Keywords.Length; i++)
    {
        int Pointer = 0;
        int Index = 0;
        while(true)
        {
            Index = CSS.Text.IndexOf(Keywords[i], Pointer);
            if(Index == -1)
                break;
            CSS.Select(Index, Keywords[i].Length);
            CSS.SelectionColor = Colours[i];
            Pointer = Index + Keywords[i].Length;
        }
    }
}

Answer 1

It depends on how flexible you want to be.

A simple solution would be to not take the length of the highlight area from the keyword but from some other source:

var highlightLengthOverrides = new Dictionary<string, int> { { "#", 7 } };

int highlightLength;
if(!highlightLengthOverrides.TryGetValue(Keywords[i], out highlightLength))
    highlightLength = Keywords[i].Length;
CSS.Select(Index, highlightLength);
CSS.SelectionColor = Colours[i];
Pointer = Index + highlightLength;

Please note that this is really a very simple implementation. It only works as long as there are always exactly 6 digits after the hash sign.

Other alternatives would be:

• Write or employ a full blown tokenizer
• Use regular expressions as keywords.