The elements in an array can be sorted in alphabetical or numerical order, descending or ascending.
PHP - Sort Functions For Arrays
In this chapter, we will go through the following PHP array sort functions:
sort[]
- sort arrays in ascending orderrsort[]
- sort arrays in descending orderasort[]
- sort associative arrays in ascending order, according to the valueksort[]
- sort associative arrays in ascending order, according to the keyarsort[]
- sort associative arrays in descending order, according to the valuekrsort[]
- sort associative arrays in descending order, according to the key
Sort Array in Ascending Order - sort[]
The following example sorts the elements of the $cars array in ascending alphabetical order:
Example
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The following example sorts the elements of the $numbers array in ascending numerical order:
Sort Array in Descending Order - rsort[]
The following example sorts the elements of the $cars array in descending alphabetical order:
Example
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The following example sorts the elements of the $numbers array in descending numerical order:
Sort Array [Ascending Order], According to Value - asort[]
The following example sorts an associative array in ascending order, according to the value:
Example
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Sort Array [Ascending Order], According to Key - ksort[]
The following example sorts an associative array in ascending order, according to the key:
Example
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Sort Array [Descending Order], According to Value - arsort[]
The following example sorts an associative array in descending order, according to the value:
Example
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Sort Array [Descending Order], According to Key - krsort[]
The following example sorts an associative array in descending order, according to the key:
Example
Try it Yourself »
Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array Reference.
The reference contains a brief description, and examples of use, for each function!
PHP Exercises
PHP has several functions that deal with sorting arrays, and this document exists to help sort it all out.
The main differences are:
- Some sort based on the array keys, whereas others by the values:
$array['key'] = 'value';
- Whether or not the correlation between the keys and values are maintained after the sort, which may mean the keys are reset numerically [0,1,2 ...]
- The order of the sort: alphabetical, ascending [low to high], descending [high to low], natural, random, or user defined
- Note: All of these sort functions act directly on the array variable itself, as opposed to returning a new sorted array
- If any of these sort functions evaluates two members as equal then they retain their original order. Prior to PHP 8.0.0, their order were undefined [the sorting was not stable].
array_multisort[] | value | string keys yes, int keys no | first array or sort options | array_walk[] |
asort[] | value | yes | ascending | arsort[] |
arsort[] | value | yes | descending | asort[] |
krsort[] | key | yes | descending | ksort[] |
ksort[] | key | yes | ascending | krsort[] |
natcasesort[] | value | yes | natural, case insensitive | natsort[] |
natsort[] | value | yes | natural | natcasesort[] |
rsort[] | value | no | descending | sort[] |
shuffle[] | value | no | random | array_rand[] |
sort[] | value | no | ascending | rsort[] |
uasort[] | value | yes | user defined | uksort[] |
uksort[] | key | yes | user defined | uasort[] |
usort[] | value | no | user defined | uasort[] |
"Matthew Rice" ¶
9 years ago
While this may seem obvious, user-defined array sorting functions [ uksort[], uasort[], usort[] ] will *not* be called if the array does not have *at least two values in it*.
The following code:
Will output:
string[4] "val3"
string[4] "val2"
The first array doesn't get sent to the function.
Please, under no circumstance, place any logic that modifies values, or applies non-sorting business logic in these functions as they will not always be executed.
oculiz at gmail dot com ¶
11 years ago
Another way to do a case case-insensitive sort by key would simply be:
Since strcasecmp is already predefined in php it saves you the trouble to actually write the comparison function yourself.
Hayley Watson ¶
5 years ago
Stabilizing the sort functions [in this case, usort].
Tags each array element with its original position in the array so that when the comparison function returns 0 the tie can be broken to put the earlier element first.