How can I truncate my strings with a “…” if they are too long?

Question

Hope somebody has a good idea. I have strings like this:

abcdefg
abcde
abc

What I need is for them to be trucated to show like this if more

Answer 1

All very good answers, but to clean it up just a little, if your strings are sentences, don't break your string in the middle of a word.

private string TruncateForDisplay(this string value, int length)
{
  if (string.IsNullOrEmpty(value)) return string.Empty;
  var returnValue = value;
  if (value.Length > length)
  {
    var tmp = value.Substring(0, length) ;
    if (tmp.LastIndexOf(' ') > 0)
       returnValue = tmp.Substring(0, tmp.LastIndexOf(' ') ) + " ...";
  }                
  return returnValue;
}