I have this array:
$array = array('E1211', 'E2172', 'E2181', 'E233', 'E241', 'E286');
I need to order first by first number-letter, i.e. E1, E2, E3, E4... followed by ordered numbers from lowest to highest.
Desired order would be: E1211, E233, E241, E286, E2172, E2181
If I do sort($array);, the order will incorrectly be: "E1211", "E2172", "E2181", "E233", "E241" "E286".
If I do natsort($array);, it will incorrectly order by numbers from lowest to highest: "E233", "E241", "E286", "E1211", "E2172", "E2181"
Use usort() with a custom comparison function to split the strings and compare the portions.
<?php
$array = array('E1211','E2172','E2181','E233','E241','E286');
usort($array, function($a, $b){
$pfxA = substr($a,0,2); // Get the first two characters of each string
$pfxB = substr($b,0,2);
if ( $pfxA !== $pfxB) {return $pfxA<=>$pfxB;} // If they're not equal, return the spaceship comparison
return (int)substr($a,2)<=>(int)substr($b,2); // Prefixes are equal. Convert the rest to integers and return the spaceship comparison.
});
var_dump($array);
Output:
array(6) {
[0]=>
string(5) "E1211"
[1]=>
string(4) "E233"
[2]=>
string(4) "E241"
[3]=>
string(4) "E286"
[4]=>
string(5) "E2172"
[5]=>
string(5) "E2181"
}