<?php
function number_string ($n = 5, $order = 'desc')
{
    $boom='';
    $boom = $n . $boom;
    if ($n >= 1 )
    {number_string($n - 1,$boom);}
 
    $N = (string)$boom;
 
    $str_len=strlen($N)-1;
 
if ($order==='desc')
{
    $desc='';
    for($i=$str_len;$i>=0;$i--)
    {
        $desc.=$N{$i};
    }
    return  $desc;
}
 
if ($order==='asc')
{
    $asc='';
    for($j=0;$j<=$str_len;$j++)
    {
        $asc.=$N{$j};
    }
    return $asc;
}
 
 
 
}
 
echo number_string();
 

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