Zmazanie [quote]

[quote][/quote]

[quote][quote]fsfsf[/quote]sfsfs[/quote]

<?php
$str = 'abcd [quote][quote]test2[/quote]test3[/quote]jenp';
$level = 0;
$offset = 0;
$result = '';

while($offset < strlen($str))
{
  $c = substr($str, $offset, 1);
  switch($c)
  {
    case '[':
      if(substr($str, $offset, 7) == '[quote]')
      {
        $level += 1;
        $offset += 7;//strlen('[quote]')
      }
      if(substr($str, $offset, 8) == '[/quote]')
      {
        $level -= 1;
        $offset += 8;//strlen('[/quote]')
      }
      break;
    default:
      ++$offset;
      if($level == 0)
        $result .= $c;
  }
}
echo $result;
?>

<?php
$str = 'abcd [quote][quote]test2[/quote]test3[/quote]jenp';
function zmen($str)
{
return preg_replace("/\[quote\][^[]*\[\/quote\]/",'',$str);
}
while($str!=zmen($str))$str=zmen($str);
echo $str;
?>