Last name usort - php

Question

I asked a similar question but still having issues when some aspects.
The way this php file is working is that a persons name is being stored in the database in the names cell, in the format John Doe(firstname lastname). So I've separated the name with this code, so surname, firstname:
foreach ($customer_names as $key => $value) {
$parts = explode(" ", $value->name);
$lastname = array_pop($parts);
$firstname = implode(" ", $parts);
$name = $lastname.", ".$firstname." ";
echo "<option value='$value->name'>$name </option>";
now that gives me a list of names like Doe, John.
However, I need to sort the names in order of the surname.
using usort. How would I do that? I've tried playing around with the code, but still is showing up in the order of the first name (set by the db query).
Still a bit new to usort functionality.

Answer 1

This should work:
usort($customer_names, function($customer1, $customer2) {
return strcmp(
substr($customer1->name, strrpos($customer1->name, " ")),
substr($customer2->name, strrpos($customer2->name, " "))
);
});
Your $customer_names array will then be sorted by the last name of the customer. Last name means the string after the last space, e.g. John Doe would be Doe. Mary Lou Foo would be Foo.
Please refer to http://php.net to learn more about the used functions.

Answer 2

//Program for sorting list of names according to last name
<?php
class array_sort
{
public $temp;
public function alhsort(array $sorted)
{
for($i=0; $i<count($sorted)-1; $i++){
for($j=$i+1; $j<count($sorted); $j++){
if(strcasecmp(end(explode(' ', $sorted[$i])), end(explode(' ', $sorted[$j])))>0){
$temp = $sorted[$i];
$sorted[$i] = $sorted[$j];
$sorted[$j] = $temp;
}
}
}
return $sorted;
}
}
$sortarray = new array_sort();
print_r($sortarray->alhsort(array('Ayush Jain', 'Abhishek Gupta', 'Rahul Rajput', 'Kapil Patel', 'Shobit Shrivastav', 'Hitesh Gupta')));
?>