PHP INTERVIEW · Episode 05

PHP sorting: sort() vs asort() vs ksort()

Which one keeps your keys, and which sorts by them?

ep5_array_sorting.php

<?php
$scores = [
    "Rahul"  => 85,
    "Anshul" => 72,
    "Manish" => 90,
    "Vikash" => 65,
];

$normalSort = $aSort = $kSort =  $scores;

sort($normalSort);
asort($aSort);
ksort($kSort);

Output

Normal sort by sort() function

Array
(
    [0] => 65
    [1] => 72
    [2] => 85
    [3] => 90
)

       A sort by asort() function
       Array
(
    [Vikash] => 65
    [Anshul] => 72
    [Rahul] => 85
    [Manish] => 90
)

        K sort by ksort() function
       Array
(
    [Anshul] => 72
    [Manish] => 90
    [Rahul] => 85
    [Vikash] => 65
)

The Question

PHP has a whole family of sort functions, and they look almost identical. Interviewers want to know if you understand which one keeps your keys and which sorts by key vs by value.

Explanation

sort() sorts the array by its values (ascending) and re-indexes it — the original keys are thrown away and replaced with 0, 1, 2… Use it for plain lists where keys don’t matter.

asort() also sorts by value, but it keeps each key attached to its value. Perfect for associative data like name => score, where you still need to know whose score is whose.

ksort() ignores the values and sorts by key instead (here, names alphabetically).

The rest of the family

Each has a reverse twin: rsort(), arsort(), krsort() do the same jobs in descending order. And usort() lets you sort by your own comparison function.

Key takeaway: sort() = values, keys reset. asort() = values, keys kept. ksort() = by key.

Memory trick: read the letters — a = keep keys (associative), k = by key, r = reverse. So arsort() = associative + reverse. Also note: these sort in place and return true/false, not the sorted array.

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