// example from: http://www.codestructs.com/2011/11/syntax-highlighting-in-richtextbox_23.html
private void RichTextBox1_TextChanged(object sender, EventArgs e)
{
int iSelStart = RichTextBox1.SelectionStart;
int iSelLength = RichTextBox1.SelectionLength;
string tokens = "(auto|double|int|struct|break|else|long|switch|case|enum|register|typedef|char|extern|return|union|const|float|short|unsigned|continue|for|signed|void|default|goto|sizeof|volatile|do|if|static|while)";
Regex rex = new Regex(tokens);
MatchCollection mc = rex.Matches(RichTextBox1.Text);
int iStart = RichTextBox1.SelectionStart;
foreach (Match m in mc)
{
int iStartIndex = m.Index;
int iStopIndex = m.Length;
RichTextBox1.Select(iStartIndex, iStopIndex);
RichTextBox1.SelectionColor = Color.Blue;
RichTextBox1.SelectionStart = iStart;
RichTextBox1.SelectionColor = Color.Black;
}
RichTextBox1.SelectionStart = iSelStart;
RichTextBox1.SelectionLength = iSelLength;
}
Weiterführende Beispiele: