protected function extractCountryCode(&$fullNumber, &$nationalNumber)
{
if (mb_strlen($fullNumber) == 0 || $fullNumber[0] == '0') {
// Country codes do not begin with a '0'.
return 0;
}
$numberLength = mb_strlen($fullNumber);
for ($i = 1; $i <= static::MAX_LENGTH_COUNTRY_CODE && $i <= $numberLength; $i++) {
$potentialCountryCode = (int) substr($fullNumber, 0, $i);
if (isset($this->countryCallingCodeToRegionCodeMap[$potentialCountryCode])) {
$nationalNumber .= substr($fullNumber, $i);
return $potentialCountryCode;
}
}
return 0;
}