codice:
$lettere = array(' ','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');
$numeri = array('00','01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26');
$lettere_l = sizeof($lettere);
$string = 'prova';
$string_l = strlen($string);
$string_criptata = '';
for ($x=0;$x<$string_l;$x++){
$lettera = $string{$x};
for ($y=0;$y<$lettere_l;$y++){
if($lettera==$lettere[$y]){ $lettera_c = $numeri[$y]; }
}
$string_criptata = $string_criptata.$lettera_c;
}