Calculating an Age from Date of Birth

Wildhoney · 09-21-2007, 04:11 PM

If you're particularly nosey then calculating an individual's age from their date of birth can be fascinating. Although there is a way to calculate the age using MySQL alone, MySQL shouldn't really be used as a calculator.

The following function will take a time stamp and output you the user's age.

PHP Code:


			
function getAge($iTimestamp) 

{

    $iAge = date('Y') - date('Y', $iTimestamp);

    

    if(date('n') < date('n', $iTimestamp)) 

    {

        return --$iAge;

    } 

    elseif(date('n') == date('n', $iTimestamp)) 

    {

        if(date('j') < date('j', $iTimestamp)) 

        {

            return $iAge - 1;

        } 

        else 

        {

            return $iAge;

        }

    } 

    else 

    {

        return $iAge;

    }

}

Just remember to feed in a time stamp.

Village Idiot · 09-21-2007, 08:14 PM

you could just do this

PHP Code:


			
function bday($day)
{
$age = time() - $bday;
$years = date("Y",$age);
return $years;
}

Wildhoney · 09-21-2007, 08:27 PM

I tried that, Village Idiot, but all I appear to get back is 1991:

PHP Code:


			
echo bday('10-10-1985');

function bday($bday)
{
    $age = time() - strtotime($bday);
    $years = date("Y",$age);
    return $years;
}

Salathe · 09-21-2007, 10:58 PM

I'm not sure of the logic on Village Idiot's function (1. Get difference between now and birth date in seconds; 2. Push that into date function, which accepts timestamps, not random seconds; 3. Expect to retrieve a year).

Wildhoney's code, whilst I don't see any problems with the functionality, is a wee bit of a mess (mostly because I never really liked elseifs). The code can be squished into the following function which behaves identically to Wildhoney's but, I think, is a little neater.

PHP Code:


			
function getAgeSalathe($iTimestamp)

{

    // See http://php.net/date for what the first arguments mean.

    $iDiffYear  = date('Y') - date('Y', $iTimestamp);

    $iDiffMonth = date('n') - date('n', $iTimestamp);

    $iDiffDay   = date('j') - date('j', $iTimestamp);

    

    // If birthday has not happen yet for this year, subtract 1.

    if ($iDiffMonth < 0 || ($iDiffMonth == 0 && $iDiffDay < 0))

    {

        $iDiffYear--;

    }

        

    return $iDiffYear;

}