RichTextBox Syntax Highlighting

highlight.cs

private void Highligh(RichTextBox rtb) {
  String[] keywords = {
    "@echo",
    "echo",
    "pause",
    "set",
    "cls",
    "exit",
    "del",
    "erase",
    "exit"
  };
  String[] keywordsControl = {
    "if",
    "for",
    "goto",
    "call"
  };

  string[] code = rtb.Lines;
  rtb.Clear();

  for (int i = 0; i < code.Length; i++) {
    if (code.Length - 1 != i) code[i] += System.Environment.NewLine; //ajout du retour chariot dans la chaine de caracteres
    String[] words = new Regex("([^\\s]+)").Split(code[i]);
    foreach(string word in words) {
      if (word.Length > 1) //aucune vérification sur les espaces
      {
        if (keywords.Contains(word.ToLower())) { //coloration des commandes
          rtb.SelectionFont = new Font(rtb.SelectionFont.FontFamily, rtb.SelectionFont.Size, FontStyle.Bold);
          rtb.SelectionColor = System.Drawing.ColorTranslator.FromHtml("#D56AA0"); //Rouge
        }
        else if (keywordsControl.Contains(word.ToLower())) { //coloration des structures de controle
          rtb.SelectionFont = new Font(rtb.SelectionFont.FontFamily, rtb.SelectionFont.Size, FontStyle.Bold);
          rtb.SelectionColor = System.Drawing.ColorTranslator.FromHtml("#6BBABF"); //Cyan
        }
        else if (word.Substring(0, 1) == word.Substring(word.Length - 1, 1) && word.Substring(0, 1) == "%") { //coloration des variables
          rtb.SelectionFont = new Font(rtb.SelectionFont.FontFamily, rtb.SelectionFont.Size, FontStyle.Bold);
          rtb.SelectionColor = System.Drawing.ColorTranslator.FromHtml("#F1BA59"); //Orange
        }
      }
      rtb.SelectedText = word;
      rtb.SelectionColor = System.Drawing.ColorTranslator.FromHtml("#F2F5F2");
      rtb.SelectionFont = new Font(rtb.SelectionFont.FontFamily, rtb.SelectionFont.Size, FontStyle.Regular); //Blanc
    }
  }
}