Ciclo e return var

[bubu sette sette]

function contatore(){
$var = "";
$visite = "2000";
$num = 0;
while ($num < strlen($visite)){ 
$imm = substr($visite, $num, 1);
$url = "http://www.sito.it/images/contatore";

if(file_exists("$url/$digit.jpg")){
$var .= "<img src=\"$url/$imm.jpg\" border=0>";
}else{
$var .= "<img src=\"$url/$imm.gif\" border=0>";
}

$num++;
}

return $var;
}