Sorting multidimensional array by key alphabetically

Question

Trying to sort by this multidimensional array by screen name:

//Looping through this for each member of a group
unset($member_info);
$member_info->id           =   $member->id;
$member_info->screen_name  =   $member->screen_name;
$member_info->first_name   =   $member->first_name;
$member_info->last_name    =   $member->last_name;
$member_info->email        =   $member->email;

//Sort member_info by screen name
$member_array = sort_by_array_key($member_info,$member_info->screen_name,'ASC');
$member_list[] = $member_array;

Sort function:

function sort_by_array_key($array,$sort_key,$dir = 'ASC') {
    usort($array, function($a,$b) use ($sort_key){
        return strnatcasecmp($a["$sort_key"], $b["$sort_key"]);
    });
    if ( $dir == 'DESC' ) { return array_reverse($array); }
    else { return $array; }
}

As an example, screen names are currently in this order even after I run the sort function:

newUser
Chris
Carlos
Jason

I am probably applying the sort at the wrong time but after looking at other similar examples here I was having trouble with this, any help is appreciated, thanks!

Answer 1

First of all, you're sorting an individual item there, where you probably want to sort the actual list, $member_list. Also, you're trying to sort an array where you initialize an object. Either initialize an array or sort an object.

If I assume you really want to play with arrays, like you imply on the subject, this might be something you're trying to do:

<?php

$member_info = Array();
$member_info['id']           =   '1';
$member_info['screen_name']  =   'Chris';
$member_info['first_name']   =   '';
$member_info['last_name']    =   '';
$member_info['email']        =   '';

$member_list[] = $member_info;

$member_info = Array();
$member_info['id']           =   '2';
$member_info['screen_name']  =   'Carlos';
$member_info['first_name']   =   '';
$member_info['last_name']    =   '';
$member_info['email']        =   '';

$member_list[] = $member_info;

$member_info = Array();
$member_info['id']           =   '3';
$member_info['screen_name']  =   'Jason';
$member_info['first_name']   =   '';
$member_info['last_name']    =   '';
$member_info['email']        =   '';

$member_list[] = $member_info;


//Sort member_list by screen name
$member_list = sort_by_array_key($member_list,'screen_name','ASC');

function sort_by_array_key($array,$sort_key,$dir = 'ASC') {
    usort($array, function($a,$b) use ($sort_key){
        return strnatcasecmp($a["$sort_key"], $b["$sort_key"]);
    });
    if ( $dir == 'DESC' ) { return array_reverse($array); }
    else { return $array; }
}

print_r($member_list);

/*
Array
(
    [0] => Array
        (
            [id] => 2
            [screen_name] => Carlos
            [first_name] =>
            [last_name] =>
            [email] =>
        )

    [1] => Array
        (
            [id] => 1
            [screen_name] => Chris
            [first_name] =>
            [last_name] =>
            [email] =>
        )

    [2] => Array
        (
            [id] => 3
            [screen_name] => Jason
            [first_name] =>
            [last_name] =>
            [email] =>
        )

)
*/

Answer 2

ksort - "Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays."

See the manual