Php uasort
From w3cyberlearnings
Contents |
PHP function uasort
This function sorts array by using a user-defined function. Keep array keys or array index while it sorts the array value.
Syntax uasort
- array: array input
- callback: user-defined function
uasort(array,callback);
callback return
- Return 0 when $a=$b
- Return 1 when $a>$b
- Return -1 when $a<$b
Note
The uasort function uses quicksort algorithm to sort.
Example 1
<?php
function sort2($v1, $v2) {
if ($v1 == $v2) {
return 0;
} else if ($v1 > $v2) {
return 1;
} else {
return -1;
}
}
$score0 = array(
'a' => 1,
'b' => 2,
'c' => 16,
'd' => 23,
'e' => 1,
'f' => -1,
'h' => -9
);
$score1 = array(
'a' => 1,
'b' => 2,
'c' => 16,
'd' => 23,
'e' => 1,
'f' => -1,
'h' => -9
);
$score2 = array(
'a' => 1,
'b' => 2,
'c' => 16,
'd' => 23,
'e' => 1,
'f' => -1,
'h' => -9
);
// withou sort
print_r($score0);
// sort keep key and value
uasort($score0, "sort2");
// sort with key
uasort($score1, "sort2");
// sort with value
usort($score2, "sort2");
print_r($score0);
print_r($score1);
print_r($score2);
?>
Output
// without sorting
Array
(
[a] => 1
[b] => 2
[c] => 16
[d] => 23
[e] => 1
[f] => -1
[h] => -9
)
// using uasort
// keep array key and value
// sort by value
Array
(
[h] => -9
[f] => -1
[e] => 1
[a] => 1
[b] => 2
[c] => 16
[d] => 23
)
// using uasort
// sort by key
Array
(
[a] => 1
[b] => 2
[c] => 16
[d] => 23
[e] => 1
[f] => -1
[h] => -9
)
// using usort
// sort by value
// but the array key is not keep
Array
(
[0] => -9
[1] => -1
[2] => 1
[3] => 1
[4] => 2
[5] => 16
[6] => 23
)
Example 2
<?php
$list = array('bc', 'ca', 'dd','aa', 'ab', 'bb');
print_r($list);
uasort($list, "strcmp");
print_r($list);
?>
Output
// without soring
Array
(
[0] => bc
[1] => ca
[2] => dd
[3] => aa
[4] => ab
[5] => bb
)
// using uasort
// sort and keeps index as it is
Array
(
[3] => aa
[4] => ab
[5] => bb
[0] => bc
[1] => ca
[2] => dd
)
Related Links
- array_change_key_case
- array_chunk
- array_combine
- array_count_values
- array_diff_assoc
- array_diff_key
- array_diff_uassoc
- array_diff_ukey
- array_diff
- array_fill_keys
- array_fill
- array_filter
- array_flip
- array_intersect_assoc
- array_intersect_key
- array_intersect_uassoc
- array_intersect_ukey
- array_intersect
- array_key_ exists
- array_keys
