Gestione file...

[dottwatson]

semplice

<?php
$tmp=array();
$utenti=file('xxx.txt');
foreach($utenti as $line)
  {
  $blocks=explode(':',$line);
  unset($blocks[count($blocks)-1]);
  $username=$blocks[0];

  if (isset($tmp[$username])) $tmp[$username]++;
  else                        $tmp[$username]=0;

  $blocks[count($blocks)-1]=$tmp[$username];
  echo implode(':',$blocks)."
";
  }
?>