cal_to_jd: getting Julian day count

$day = cal_to_jd(CAL_GREGORIAN,2,2,2103);
echo $day;

cal_to_jd('calendar', month, day , year )

Example: Converting Gregorian Date to Julian Day

$jd = cal_to_jd(CAL_GREGORIAN, 10, 8, 2023);
echo "Julian Day: " . $jd;  // Output: Julian Day: 2460219

Example: Handling Out-of-Range Dates

$jd = cal_to_jd(CAL_GREGORIAN, 15, 50, 2023);
if ($jd === false) {
    echo "Invalid date provided!";
}