Age from date of birth

[dannylewin]

I have this script i found that converts your date of birth to your age... But for some people it is adding an extra year!

i.e. date of birth 27th Sept 1978 (27) its showing as 28

heres the code:

$yage = $row_userDetails['dob_y'];  	// $yage is a string
$yage += 0;   	// $yage is now an integer--year of birth
$mage = $row_userDetails['dob_m'];  // $mage is string
$mage += 0;   	// $mage is now an integer--month of birth
$dage = $row_userDetails['dob_d'];  // $dage is string
$dage += 0;   	// $dage is now an integer--day of birth
$leap = date("L");  //adds 0 if not leap year, +1 if it is			
$nowday = date("d");	//day part of today's date
$nowday += 0;	// convert date string to true integer
$lnowday = ($nowday + $leap); //leapyear consideration
$nowmonth =date("m");	//month part of today's date
$nowmonth += 0;	// convert date string to true integer
$myyear = date("Y"); 	//this year as 4 digit number		
$age = ($myyear-$yage);  //Almost there!
if (($nowmonth < $mage) OR (($nowmonth < $mage) AND ($lnowday < $dage))) {
$age=$age-1;}
$length=strlen($age); 
if (($length < "2")) {
$age = "0".$age."";
}

Has anyone any ideas how to fix this??

Thanks in advance!

Danny

[NogDog]

function get_age($birthDate)
{
   $dob = strtotime($birthDate);
   if(!$dob)
   {
      user_error("get_age(): '$birthDate' is not a recognizable date format",
            E_USER_WARNING);
      return(FALSE);
   }
   list($nowYear, $nowDay) = explode(',', date('Y,z'));
   list($dobYear, $dobDay) = explode(',', date('Y,z', $dob));
   $age = $nowYear - $dobYear;
   $age -= ($nowDay < $dobDay) ? 1 : 0;
   return ($age < 0) ? FALSE : $age;
}
// usage:
echo "I am ".get_age('1956-10-17')." years old.";

[MarkR]

I have this tangential solution; I've converted a date into an integer, as if each month had 100 days and each year 100 months. This means we get dates like 20060917

Then I just subtract one from the other and divide by 10000, this gives me the answer in calendar years (round down, obviously!).

/*
 * Creates an integer such as
 * 20060503
 * From the date/time specified (GMT)
 * which can be used to calculate the number of calendar months
 * etc between two dates and similar stuff.
 */
function GetDecimalDays($when)
{
        return (int) gmdate("Ymd", $when);
}

/*
 * Returns the difference between two dates in whole calendar years.
 * Rounds down.
 */
function TimeDifferenceYears($to, $from)
{
        $daysdiff = GetDecimalDays($to) - GetDecimalDays($from);
        return (int) ($daysdiff / 10000);
}

This example works with timestamps in GMT, which is my preferred form of moving dates around internally (of course in the database they're all stored as datetimes in GMT; I assume that everyone was born at midnight GMT).

Mark

[dannylewin]

NogDog:

I got this error using your method:

Warning: date(): Windows does not support dates prior to midnight (00:00:00), January 1, 1970 in ~~~~~~

How would i use your method MarkR?

Thanks,
Danny

[Installer]

nm: Misread post.

[MarkR]

dannylewin wrote:

How would i use your method MarkR?

It would suffer the same problem.

I have only deployed this on systems where date() and its friends work on negative timestamps (i.e. before 1970).

It's always worked for me; I've not tried it with anyone with a DOB earlier than about 1930.

Mark

[Weedpacket]

MarkR wrote:

It would suffer the same problem.

Not really; your GetDecimalDays takes a Unix timestamp and converts it to year, month, and day. But in the original problem the year, month and day have already been separated out, and just need to be concatenated together into a string. Do that for both dates, subtract, and divide. Done.