- base_convert: documentation ( source)
- strcmp: documentation ( source)
<?php
$val = 17;
$fr = 10;
$to = 16;
if (strcmp($val, base_convert($val, $fr, $fr) )) {
echo "$val isn't purely in base $fr";
} else {
$newval = base_convert($val, $fr, $to);
echo "new val is $newval";
}