RichTextBox --> Change Font for specific line

Question

I want to change the font in a specific line. Here's my code...

string[] textBoxLines = richTextBox1.Lines;
foreach (string line in textBoxLines)
{
   if(line.StartsWith("-->"))
   {
   //here is my problem, how to can change the font in the spectific line...
   }
}

Answer 1

string[] textBoxLines = richTextBox1.Lines;
for (int i = 0; i < textBoxLines.Length; i++)
{
    string line = textBoxLines[i];
    if (line.StartsWith("-->"))
    {
        richTextBox1.SelectionStart = richTextBox1.GetFirstCharIndexFromLine(i);
        richTextBox1.SelectionLength = line.Length;
        richTextBox1.SelectionFont = yourFont;
    }
}
richTextBox1.SelectionLength = 0;//Unselect the selection