PHP - sort arrays within assoc array - php

Question

I promise you I've had a look at the many existing SO Qs about PHP sorting, including this mega one
I've got a PHP associative array, with strings as keys. Each value is an array of integers. I want to sort each array of integers, in simple ascending numerical order. I'm convinced this should be easy, and I've found enough examples that I think I should be doing the right thing, but it's not quite working, so there's a typo or I'm an idiot or something...
PHP:
//Each fruit corresponds to an array (series) of integers
$data = [
'banana' => [
1,3,2
],
'orange' => [
5,1,3
]
];
echo "Before sort:\n";
var_dump($data);
//For each fruit, I want to order the numbers
foreach ($data as $key => $series)
{
//Sort array of integers
sort($series);
//NB I wasn't sure about value/reference details of foreach loops, so I also tried
//retrieving a series into a variable, sorting, and then reassigning back to the same key
}
echo "\n\nAfter sort:\n";
var_dump($data);
Output:
Before sort:
array(2) {
'banana' =>
array(3) {
[0] =>
int(1)
[1] =>
int(3)
[2] =>
int(2)
}
'orange' =>
array(3) {
[0] =>
int(5)
[1] =>
int(1)
[2] =>
int(3)
}
}
After sort:
array(2) {
'banana' =>
array(3) {
[0] =>
int(1)
[1] =>
int(3)
[2] =>
int(2)
}
'orange' =>
array(3) {
[0] =>
int(5)
[1] =>
int(1)
[2] =>
int(3)
}
}
As you can see, in the output the inner arrays of integers have not been sorted. What am I doing wrong? (PHP 5.5.9, Windows 7)

Answer 1

Use a reference &:
foreach ($data as $key => &$series)
{
//Sort array of integers
sort($series);
// OR
// sort($data[$key]);
}