Regular Expression (Regex) to validate date and the format of the date (dd/mm/yyyy). I use the regex to check if the data provided is in the required format. Then I use the PHP function checkdate($dd, $mm, $yyyy) to check if the values provided are right. For example, the function will return FALSE if the user provide a date like 30/02/2013, or …

check_date.php

<?php
    // function to check dates
    public function date_check($date)
    {
        $exp_regular = '/^(\d{2})[\/](\d{2})[\/](\d{4})/';
        $ret = preg_match($exp_regular, $date, $matches);
        
        if($ret === 1)
        {
            $dd = $matches[1];
            $mm = $matches[2];
            $yyyy = $matches[3];
            
            if (checkdate($mm, $dd, $yyyy))
            { 
                echo "The date is correct";
                return TRUE;
            }
            else
            {
                echo "The date is wrong";
                return FALSE;
            }
        }
        else
        {
            echo "The date must have this format: dd/mm/yyyy";
            return FALSE;
        }
    }
    
    // Hope it helps
    
    // Any problem, report then in the comments.
    // Thanks!
?>