- substr: documentation ( source)
- str_repeat: documentation ( source)
- min: documentation ( source)
<?php
function asterisk($password)
{
$count = min(strlen($password), 4);
$passwordAsterisk = str_repeat('*', $count) . substr($password, $count);
echo $password . ' => ' . $passwordAsterisk . PHP_EOL;
return $passwordAsterisk;
}
asterisk('abcdef');
asterisk('abc');
asterisk('');