Array Order maintaining/reggistering original position (php) - php

Question

I have an array like this one
$state[1]='FG';
$state[2]='BU';
$state[3]='CA';
...
$state[150]='YT'
What I need is to have the $state array ordered from A to Z and maintain, in some structure, the original order of the array.
Something like:
$state_ordered['BU']=2;
$state_ordered['CA']=3;
and so on.
I have the array in the first form in an include file: which is the most performant way and which is the related structure to use in order to have the best solution?
The include is done at each homepage opening...
Thanks in advance,
A.

Answer 1

Well, you can array_flip the array, thus making 'values' be the original indexes, and then sort it by keys...
$b = array_flip($a);
ksort($b);
then work with $b keys , but the values reflect original order

Answer 2

You want array_flip(), which switches the key and value pairs.
Example #2 from the link:
$trans = array("a" => 1, "b" => 1, "c" => 2);
$trans = array_flip($trans);
print_r($trans);
Outputs:
Array
(
[1] => b
[2] => c
)

Answer 3

PHP has quite a few functions for sorting arrays. You could sort your array alphabetically by the values it holds by using asort() and then retrieve the index using array_search()
as such:
?php
$state[1]='FG';
$state[2]='BU';
$state[3]='CA';
asort($state);
$key = array_search('BU',$state);
print $state[$key] . PHP_EOL;
print_r($state);
this will output
BU
Array
(
[2] => BU
[3] => CA
[1] => FG
)
which as you can see keeps the original index values of your array. This does mean however that when you loop over your array without using the index directly, like when you use foreach that you then loop over it in the resorted order:
foreach($state as $key=>$value){
print "$key: $value" . PHP_EOL;
}
2: BU
3: CA
1: FG
You'd need to use ksort on the array first to sort it by index again before getting the regular foreach behaviour that you'd probably want/expect.
ksort($state);
foreach($state as $key=>$value){
print "$key: $value" . PHP_EOL;
}
1: FG
2: BU
3: CA
Looping using a for structure with numeric index values always works correcty of course. Be warned that these functions get passed your array by reference, meaning that they work on the 'live array' and not on a copy, you'll need to make your own copy first if you want one, more info in References Explained.