title: PHP regular expression - filter number only
body: <p>I know this might sound as really dummy question, but I'm trying to ensure that the provided string is of a number / decimal format to use it later on with PHP's number_format() function.</p>
  
  <p>How would I do it - say someone is typing 15:00 into the text field - what regular expression and php function should I use to remove the colon from it and make it only return the valid characters.</p>
  
  <p>preg_match() returns array - so I can't pass the result to number_format() unless I implode() it or something like this.</p>
  
  <p>Your help would be very much appreciated.</p>