Sort a multidimensional array by Last name in php - php

Question

Is it possible to sort (with php) an array like this by last name:
$array = array(
array("name" => "Mary Johnson","age" => 43),
array("name" => "Amanda Miller","age" => 23),
array("name" => "James Brown","age" => 47),
array("name" => "Patricia Williams","age" => 31),
array("name" => "Michael Davis","age" => 15),
array("name" => "Sarah Miller","age" => 35),
array("name" => "Patrick Miller","age" => 44)
);
<?php
// A function to sort by last name.
function lastNameSort($a, $b) {
$aLast = end(explode(' ', $a));
$bLast = end(explode(' ', $b));
return strcasecmp($aLast, $bLast);
}
// The array of data.
$array = array(
array("name" => "Mary Johnson","age" => 43),
array("name" => "Amanda Miller","age" => 23),
array("name" => "James Brown","age" => 47),
array("name" => "Patricia Williams","age" => 31),
array("name" => "Michael Davis","age" => 15),
array("name" => "Sarah Miller","age" => 35),
array("name" => "Patrick Miller","age" => 44)
);
// Perform the sort:
uasort($array, 'lastNameSort');
// Print the result:
print_r($array);

Answer 1

Its just an addressing issue. Amend you function as below, remember the $a and $b are arrays and not scalar variables.
$array = array(
array("name" => "Mary Johnson","age" => 43),
array("name" => "Amanda Miller","age" => 23),
array("name" => "James Brown","age" => 47),
array("name" => "Patricia Williams","age" => 31),
array("name" => "Michael Davis","age" => 15),
array("name" => "Sarah Miller","age" => 35),
array("name" => "Patrick Miller","age" => 44)
);
function sortByName($a, $b) {
$aLast = explode(' ', $a['name'])[1];
$bLast = explode(' ', $b['name'])[1];
return strcasecmp($aLast, $bLast);
}
#print_r($array);
usort($array, 'sortByName');
print_r($array);
RESULT
Array
(
[0] => Array ( [name] => James Brown [age] => 47 )
[1] => Array ( [name] => Michael Davis [age] => 15 )
[2] => Array ( [name] => Mary Johnson [age] => 43 )
[3] => Array ( [name] => Amanda Miller [age] => 23 )
[4] => Array ( [name] => Sarah Miller [age] => 35 )
[5] => Array ( [name] => Patrick Miller [age] => 44 )
[6] => Array ( [name] => Patricia Williams [age] => 31 )
)
And to get the Millers in the correct order by firstname as well as lastname, you code amend the sort function a little as below
function sortByName($a, $b) {
$t = explode(' ', $a['name']);
$aLast = $t[1] . $t[0];
$t = explode(' ', $b['name'])[1];
$bLast = $t[1] . $t[0];
return strcasecmp($aLast, $bLast);
}