Birthday function coming up short!

[techiefreak05]

i have the following code thats supposed to take a variable that holds a birthday, such as "03-24-1990",and show the age, such as "17" its not off by much, but it IS off by one year..

 

 <?php
function birthday($birthday){

list($month,$day,$year) = explode("-",$birthday);

$month_diff = date("m") - $month;

$day_diff   = date("d") - $day;

$year_diff  = date("Y") - $year;

if ($day_diff < 0 || $month_diff < 0){


$year_diff--;

}
     return $year_diff;
}
?>

 

I use that one way, like this

 

<?php
$bday="03-24-1990";
birthday($bday);
?>

 

That outputs as: 16, when it should output 17, because that's my birthday!

[btherl]

The logic here is faulty:

 

if ($day_diff < 0 || $month_diff < 0){
$year_diff--;
}

 

Look at the following cases:

 

2000-01-01

2000-01-31

2000-02-01

2000-02-31

2000-08-01

2000-08-31

2000-09-01

2000-09-31

 

That should be enough to get the logic right

[techiefreak05]

So ...

what do I do to fix it?

 

Do I pass a different variable thru the function?

[techiefreak05]

Oh! I noticed the < 0 part.

haha

So how can I make it work, I got this script froma friend and he has no idea ... I chanegd the "< 0", to "< 1" still no change.. and what does

 

$year_diff--; mean?

[btherl]

Try this one out.  I am not 100% convinced that it works, but it works for the test cases i've tried.

 

function birthday($birthday){
list($month,$day,$year) = explode("-",$birthday);
$month_diff = date("m") - $month;
$day_diff   = date("d") - $day;
$year_diff  = date("Y") - $year;
if ($day_diff < 0) {
   $month_diff--;
}
if ($month_diff < 0){
  $year_diff--;
}
return $year_diff;
}