php-regexHow to use regex in PHP to match date in "yyyy-mm-dd" format?

The following regular expression can be used to match a date in the "yyyy-mm-dd" format in PHP:

$regex = '/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/';

This expression will match a string of the form "yyyy-mm-dd" where:

• [0-9]{4}: The year is a 4-digit number
• (0[1-9]|1[0-2]): The month is a 2-digit number between 01 and 12
• (0[1-9]|[1-2][0-9]|3[0-1]): The day is a 2-digit number between 01 and 31

For example, the following code will return true if the date is in the correct format:

$date = '2020-04-30';
$regex = '/^[0-9]{4}-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])$/';

if (preg_match($regex, $date)) {
    echo 'true';
}

Output example

true

For more information about regular expressions in PHP, see the PHP documentation.

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