Validate if age is over 18 years old

Question

Just wondering, can I do this to validate that a user has entered a date over 18?

//Validate for users over 18 only
function time($then, $min)
{
    $then =          


        

Answer 1

Here is a simplified extract from what I used for a banking system in Toronto, and this always worked perfectly, taking account of leap years of 366 days.

/* $dob is date of birth in format 1980-02-21 or 21 Feb 1980
 * time() is current server unixtime
 * We convert $dob into unixtime, add 18 years, and check it against server's
 * current time to validate age of under 18
 */

if (time() < strtotime('+18 years', strtotime($dob))) {
   echo 'Client is under 18 years of age.';
   exit;
}