html and php date input field

Question

I am having issues trying to figure out how, to create an html input box for the date:

like this:

YYYY-MM-DD

I was wondering if there is a better method of doing this than me manually creating something like this, and then using the - separators to separate the YYYY-MM-DD.

I will be using regex to do some validation after the user has entered the date of birth to make sure that it is greater than 21.

<label for="dob">Age (YYYY-MM-DD)</label>
<input id="dateofbirth" type="text" name="age" maxlength="10"/><span>*</span><br />

Here is my regex for the date that will be inside function checkdate on the php side:

return preg_match('/(\d{4})-(\d{2})-(\d{2}, $date);

Set date such that it will only take input from users over 21. Currently this does not.
$date = '1974-12-03';

Answer 1

I would simply use a jquery date picker.

This way you don't have to worry about the input format and you can easily get the date entered in a single format to perform validation in javascript or PHP (if you pass the date back to the server).

Answer 2

if($age = strtotime($date)){ 
 if( ( date('Y',time()) - date('Y',$age ) >= 21 ){
  return true; 
 }else{ 
  return false; } 
}else{ 
 echo 'There seems to be something wrong with your age input'; 
}

That will verify that the user is over/equal the age of 21