Masking text code. Any shorter way?

Question

I feel like I'm reinventing wheel here. All I want it to take string and insert dashes to format social security number for display:

if (maskedText.Length <= 3)
{
   text = maskedText;
}
else
{
   text = maskedText.Substring(0, 3) + "-";

   if (maskedText.Length <= 5)
   {
      text += maskedText.Substring(3, maskedText.Length - 3);
   }
   else
   {
      text += maskedText.Substring(3, 2) + "-" 
                + maskedText.Substring(5, maskedText.Length - 5);
      if (text.Length > 11) 
         // Trim to 11 chars - this is all for SSN
         text = text.Substring(0, 11); 

   }
}

I do it for custom control in Silverlight. I wonder if there is ant built-in library or function that will do that? I do not want to add any dependencies (download size)

Answer 1

All you need to do is insert some dashes...

text  = maskedText.Insert(5, "-").Insert(3, "-");

EDIT: ok this is only a bit cleaner than the above code...

    if (maskedText.Length > 9)
        maskedText = maskedText.Substring(0, 9);
    if (maskedText.Length > 5)
        maskedText = maskedText.Insert(5, "-");
    if (maskedText.Length > 3)
        maskedText = maskedText.Insert(3, "-");
    text = maskedText;

If it were a number you could do this... but unfortunately there is no simple format statement to do this with a string.

String.Format("{0:000-00-0000}", ssnNumeric)