Most efficient way to delimit key.

Say I have a string of 16 numeric characters (i.e. 0123456789012345) what is the most efficient way to delimit it into sets like : 0123-4567-8901-2345, in PHP?

Note: I am rewriting an existing system that is painfully slow.

From stackoverflow

• Use str_split():

  $string = '0123456789012345';
  $sets = str_split($string, 4);
  print_r($sets);
  

  The output:

  Array
  (
      [0] => 0123
      [1] => 4567
      [2] => 8901
      [3] => 2345
  )
  

  Then of course to insert hyphens between the sets you just implode() them together:

  echo implode('-', $sets); // echoes '0123-4567-8901-2345'
  

  Rob : Assuming the OP wants the hyphens inserted, you'd probably then want to do implode( '-', $sets ).

  yjerem : Yeah, edited that in while you were commenting. At first I assumed he knew the implode() function.

  Unkwntech : I do, I know how to do this also, I was A) hoping for something different I didn't already know about, b) putting it out there for other persons, since I've been asked about this 3 times today.

  DreamWerx : What's the data source? If it's a DB, you can have the DB format it for you before it even gets to PHP.

• If you are looking for a more flexible approach (for e.g. phone numbers), try regular expressions:

  preg_replace('/^(\d{4})(\d{4})(\d{4})(\d{4})$/', '\1-\2-\3-\4', '0123456789012345');
  

  If you can't see, the first argument accepts four groups of four digits each. The second argument formats them, and the third argument is your input.

  Loki : I'm not sure if this wouldn't work better? preg_replace('/(\d{4})/', '-\1', '0123456789012345');

  strager : That wouldn't work, since you'd be left with a '-' hanging in the front of the output. It also kills some of the flexibility. I have edited my post to use the {4} syntax, though.

• This is a bit more general:

  <?php
  
  // arr[string] = strChunk(string, length [, length [...]] );
  function strChunk() {
      $n = func_num_args();
      $str = func_get_arg(0);
      $ret = array();
  
      if ($n >= 2) {
       for($i=1, $offs=0; $i<$n; ++$i) {
        $chars = abs( func_get_arg($i) );
        $ret[] = substr($str, $offs, $chars);
        $offs += $chars;
       }
      }
  
      return $ret;
  }
  
  echo join('-', strChunk('0123456789012345', 4, 4, 4, 4) );
  
  ?>