sorting two dimensions in PHP

sorting.php

<pre><?php

// A nice simple 2 dimensional array
$people = array(
	// array($name, $age)
	array('Jim', 20),
	array('Betty', 50),
	array('Bob', 35),
	array('Rob', 22),
	array('Rachel', 40),
);

/**
 * A custom sort function as per http://uk.php.net/manual/en/function.usort.php
 */
function order_by_age_asc($a, $b)
{
	// If age of $a is the same as age from $b
	if ($a[1] === $b[1]) {
		return 0;
	}
	
	// If $a age is less that $b age -1 otherwise +1
	// This is used to order each array from lowest to highest
	return ($a[1] < $b[1]) ? -1 : 1;
}

// This will print an array  of people sorted by age ASC
usort($people, 'order_by_age_asc');
print_r($people);

/**
 * A custom sort function as per http://uk.php.net/manual/en/function.usort.php
 */
function order_by_age_desc($a, $b)
{
	// If age of $a is the same as age from $b
	if ($a[1] === $b[1]) {
		return 0;
	}
	
	// If $a age is less that $b age +1 otherwise -1
	// This is used to order each array from highest to lowest
	return ($a[1] < $b[1]) ? 1 : -1;
}

// This will print an array  of people sorted by age DESC
usort($people, 'order_by_age_desc');
print_r($people);

// Default oldest person to first of the array
$oldest = $people[0];

// Default youngest person to first of the array
$youngest = $people[0];

foreach ($people as $_person)
{
	// If this persons ages is greater than the oldest
	// make this the oldest
	if ($oldest < $_person[1])
	{
		$oldest = $_person;
	}
	
	// Also check if lower than the youngest
	if ($youngest > $_person[1])
	{
		$youngest = $_person;
	}
}

print_r($oldest);
print_r($youngest);

The manual has an example that does exactly what you are doing here but using array_multisort().
http://php.net/array_multisort
The custom sort functions save the whole array-preparing though.

btw "shorting" in the description

Thanks for pointing that function out :)