Sorting array only using first element of an array in php

Question

I have three arrays like this:

$a1  = array('55','something1','something2','something3' );
$a2  = array('77','something14','something25','something36' ); 
$a4  = array('66.6','something15','something25','something34' );

and a array of these three like this:

$a  = array($a1,$a2,$a4 );

I know by using sort() I can sort numeric values but here what I want to sort above arraysin such a manner that sorting occurs only through first numeric element of arrays $a1,$a2 and $a4 i.e. output should be first $a1 because 55 less than 66.6 and 77 then $a4 because 66.6 is less than 77 and the $a2.I dont't want values of elements in arrays $a1 ,$a2,$a4 get changed only array $a should be rearranged nummerically.

*only array $a should be rearranged nummerically* - how that? — RomanPerekhrest, Mar 15 '17 at 21:24
Possible duplicate of [Sort Multi-dimensional Array by Value](http://stackoverflow.com/questions/2699086/sort-multi-dimensional-array-by-value) — René Höhle, Mar 15 '17 at 21:24

score 1 · Accepted Answer · answered Mar 15 '17 at 21:29

using usort

usort — Sort an array by values using a user-defined comparison function

$a1  = array('55','something1','something2','something3' );
$a2  = array('77','something14','something25','something36' ); 
$a4  = array('66.6','something15','something25','something34' );


$array = [$a1, $a2, $a4];

usort($array, function($a, $b) {
    if ($a[0] > $b[0]) {
        return 1;
    } else {
        return -1;
    }
});


print_r($array);

live example: https://3v4l.org/QnUXc

Sorting array only using first element of an array in php

1 Answers1