Simple enum for PHP < 8.1 >= 5.3.0
abstract class DaysOfWeek extends Enums
{
const SUNDAY = 0;
const MONDAY = 1;
const TUESDAY = 2;
const WEDNESDAY = 3;
const THURSDAY = 4;
const FRIDAY = 5;
const SATURDAY = 6;
}
var_dump(DaysOfWeek::isValidName('esyede')) . PHP_EOL; // bool(false)
var_dump(DaysOfWeek::isValidName('MONDAY')) . PHP_EOL; // bool(true)
var_dump(DaysOfWeek::isValidName('Monday')) . PHP_EOL; // bool(true)
var_dump(DaysOfWeek::isValidName('Monday', $strict = true)) . PHP_EOL; // bool(false)
var_dump(DaysOfWeek::isValidName(0)) . PHP_EOL; // bool(false)
var_dump(DaysOfWeek::isValidValue(0)) . PHP_EOL; // bool(true)
var_dump(DaysOfWeek::isValidValue(5)) . PHP_EOL; // bool(true)
var_dump(DaysOfWeek::isValidValue(7)) . PHP_EOL; // bool(false)
var_dump(DaysOfWeek::isValidValue('FRIDAY')) . PHP_EOL; // bool(false)