checkdate() : Checking a valid date entered by user in PHP

<?Php
echo checkdate(12,31,2017); // Output 1 
echo var_dump(checkdate(12,31,2017)); // Output bool(true) 
echo var_dump(checkdate(29,02,2017)); // Output bool(false) 
echo var_dump(checkdate(06,31,2023)); // Output bool(false) 
?>

bool checkdate (int month, int day, int year)

Using checkdate()

$m='11';
$d='31';
$y='05';
If(!checkdate($m,$d,$y)){
echo 'invalid date'; 
}else {
echo "Entry date is correct";
}

Input date from a text field

$dt=$_POST['dt'];
$dt="02/28/2007"; // Setting a date in m/d/Y format 
$arr=explode("/",$dt); // breaking string to create an array
$mm=$arr[0]; // first element of the array is month
$dd=$arr[1]; // second element is date
$yy=$arr[2]; // third element is year
If(!checkdate($mm,$dd,$yy)){
echo "invalid date";
}else {
echo "Entry date is correct";
}

$dd=$arr[0]; // first element of the array is date
$mm=$arr[1]; // second element is month
$yy=$arr[2]; // third element is year

Input date from a calendar

Date Validation using createFromFormat()

<?Php
function Date_validate($input_date, $format = 'd-m-Y')
{
    $date_obj = DateTime::createFromFormat($format, $input_date);
    return $date_obj && $date_obj->format($format) == $input_date;
}

echo Date_validate('12-12-2017'); // Output is 1
echo var_dump(Date_validate('12-12-2017')); // Output is bool(true)
echo var_dump(Date_validate('31-11-2017')); // Output is bool(false)
?>

Using date_get_last_errors()

Getting error or warning messages by using date_get_last_errors().

$date = DateTime::createFromFormat('d/m/Y', '01/13/2019'); 
// change above input  date for different messages. //
$errors = DateTime::getLastErrors();
if (!empty($errors['warning_count'])) {
    echo "Strictly speaking, input date is invalid! ( Warning ) ";
}
if (!empty($errors['error_count'])) {
    echo "input date is invalid! ( error ) ";
}

//echo "<br>Input date is : ".$date->format('Y-m-d H:i:s');

$date = DateTime::createFromFormat('d/m/Y', '01/13/2019');
Strictly speaking, input date is invalid! ( Warning )
Input date is : 2020-01-01 12:34:34

$date = DateTime::createFromFormat('d/m/Y', 'Wrong data');
input date is invalid! ( error )