Sorting Arrays
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, low to high (ascending), high to low (descending), numerical, 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 the order is undefined (the sorting is not stable).
Function name | Sorts by | Maintains key association | Order of sort | Related functions |
---|---|---|---|---|
array_multisort() | value | associative yes, numeric no | first array or sort options | array_walk() |
asort() | value | yes | low to high | arsort() |
arsort() | value | yes | high to low | asort() |
krsort() | key | yes | high to low | ksort() |
ksort() | key | yes | low to high | asort() |
natcasesort() | value | yes | natural, case insensitive | natsort() |
natsort() | value | yes | natural | natcasesort() |
rsort() | value | no | high to low | sort() |
shuffle() | value | no | random | array_rand() |
sort() | value | no | low to high | rsort() |
uasort() | value | yes | user defined | uksort() |
uksort() | key | yes | user defined | uasort() |
usort() | value | no | user defined | uasort() |
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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