title: RegEx for a string of length 0-2
body: <p>I'm trying to match a string that can be either empty or have 1 or 2 numbers in it such as the following:</p>
  
  <p>"" (empty)
  "1"
  "23"</p>
  
  <p>String with more numbers or non-numeric characters should not match.  My closest guess is the regex:</p>
  
  <p>[0-9]{0,2}</p>
  
  <p>Which I read to say "the numbers 0 through 9 occurring 0 to 2 times."  However, in practice I find that regex also matches longer strings like "333".  How is it possible to restrict string length in regular expressions?</p>