How to sort array of string by length and maintain their keys in PHP? [duplicate]

Question

There is an array of strings;

$arr=array('longstring','string','thelongeststring');

so the keys are:

0=>'longstring'
1=>'string'
2=>'thelongeststring'

I want to sort it by length of strings, from longest to shortest, but without changing their keys;

$arrSorted=array(**2**=>'thelongeststring', **0**=>'longstring', **1**=>'string');

I am working with PHP since 2 days so that is what I already know that could be helpful with this case:

...
    usort($twoDim, 'sorting');
}

function sorting($a, $b) {
    return strlen($b) - strlen($a);
}

That is giving me array with string sorted by length, but with new keys. Another thing is asort which sorts an array alphabetical and maintain its keys. But I have no idea how to do these two things in the same time...

Please help!

Community · Accepted Answer · 2023-11-14 22:27:54Z

4

Use uasort:

uasort — Sort an array with a user-defined comparison function and maintain index association

usort doesn't maintain index associations.

Use it like this:

function sortByLength ($a, $b) {
    return strlen($b) - strlen($a);
}

$arr = ['longstring', 'string', 'thelongeststring'];

uasort($arr, 'sortByLength');

print_r($arr);

eval.in demo

This returns:

Array
(
    [2] => thelongeststring
    [0] => longstring
    [1] => string
)

edited Nov 14, 2023 at 22:27

CommunityBot

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answered Oct 4, 2017 at 15:14

Ethan

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1 Comment

Willem Renzema Over a year ago

Good tip to keep in mind too, is that each sort function in the docs links to the same sorting comparison page, which makes it easy to figure out which method you need to use for your given problem: be2.php.net/manual/en/array.sorting.php

Don't Panic · Accepted Answer · 2017-10-04 15:26:09Z

4

...how to do these two things in the same time

You're almost there.

usort + asort = uasort.

edited Oct 4, 2017 at 15:26

answered Oct 4, 2017 at 15:15

Don't Panic

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