This PHP code uses date functions to output today's date and a person's date of birth. It then calculates the person's current age by comparing their birth month/day to the current month/day, accounting for whether their birthday has passed yet this year. The code outputs the dates, walks through the age calculation logic with comments, and displays the final age.

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<?php
// Part 1: Use date("xxx") with only one parameter to output TODAY's info
// such as current day, month and year.
$today_day = date('d');
$today_month = date('m');
$today_year = date('Y');
echo "Today's date is " . $today_day . '/' . $today_month . '/' . $today_year . '<br>';
// Today's date is 03/02/2014
// Part 2: My date of birth.
$dob_day = '31';
$dob_month = '01';
$dob_year = '1968';
// Output method 1: using . and strings:
echo 'My date of birth is ' . $dob_day . '/' . $dob_month . '/' . $dob_year . '<br>';
// My date of birth is 31/01/1968
// Output method 2: Using mktime( ) to create the timestamp:
$dob = mktime(0, 0, 0, $dob_month, $dob_day, $dob_year);
echo 'My date of birth is ' . date('d/m/Y', $dob) . '<br>';
// My date of birth is 31/01/1968
// Part 3: Calculate age.
if ($dob_month > $today_month) // Not yet reach birthday month this year (need to minus 1)
{
$age = $today_year - $dob_year -1;
echo 'Path 1 <br>'; // Debugging message
}
Macintosh HD:Applications:XAMPP:xamppfiles:htdocs:php:dob.php: 1/2

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elseif ($dob_month == $today_month) // Just reach birthday month this year.
{
if ($dob_day > $today_day) // Not yet reach birthday day this year (need to minus 1)
{
$age = $today_year - $dob_year -1;
echo 'Path 2 <br>'; // Debugging message
}
else // Already reach birthday day this year.
{
$age = $today_year - $dob_year;
echo 'Path 3 <br>'; // Debugging message
} // End of else for day.
}
else // Already after birthday month this year.
{
$age = $today_year - $dob_year;
echo 'Path 4 <br>'; // Debugging message
}
echo 'I am now ' . $age . ' years old. <br>';
// Path 4
// I am now 46 years old.
?>
Macintosh HD:Applications:XAMPP:xamppfiles:htdocs:php:dob.php: 2/2