Php usort
From w3cyberlearnings
Contents |
PHP function usort
This function sorts array values by using a user-defined function.
Syntax usort
- array: array input
- callback: user-defined function
usort(array,callback);
callback return
- Return 0 when $a=$b
- Return 1 when $a>$b
- Return -1 when $a<$b
Note
The usort 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;
}
}
$list = array('bc', 'ca', 'dd','aa', 'ab', 'bb');
usort($list, "sort2");
print_r($list);
?>
Output
Array
(
[0] => aa
[1] => ab
[2] => bb
[3] => bc
[4] => ca
[5] => dd
)
Example 2
<?php
function sort2($v1, $v2) {
if ($v1 == $v2) {
return 0;
} else if ($v1 > $v2) {
return 1;
} else {
return -1;
}
}
$score = array(30, 20, 1, 3, 10, 3);
usort($score, "sort2");
print_r($score);
?>
Output
Array
(
[0] => 1
[1] => 3
[2] => 3
[3] => 10
[4] => 20
[5] => 30
)
Example 3
<?php
$list = array('bc', 'ca', 'dd','aa', 'ab', 'bb');
usort($list, "strcmp");
print_r($list);
?>
Output
Array
(
[0] => aa
[1] => ab
[2] => bb
[3] => bc
[4] => ca
[5] => dd
)
Example 4
<?php
$myArray = array(1, 19, 18, 12, 56);
function compare($a, $b) {
echo "Comparing $a to $b\n";
if ($a == $b) return 0;
return ($a < $b) ? -1 : 1;
}
usort($myArray,"compare");
print_r($myArray);
?>
Output
sophal@test1:~$ php sort.php
Comparing 18 to 19
Comparing 56 to 18
Comparing 12 to 18
Comparing 1 to 18
Comparing 12 to 1
Comparing 56 to 19
Array
(
[0] => 1
[1] => 12
[2] => 18
[3] => 19
[4] => 56
)
Example 6
<?php
function sort2($v1, $v2) {
if ($v1 == $v2) {
return 0;
} else if ($v1 > $v2) {
return 1;
} else {
return -1;
}
}
$list = array(
'bc' => 32,
'ca' => 31,
'dd' => 'apple',
'aa' => 'banana',
'ab' => 'cling',
'bb' => 'soon');
usort($list, "sort2");
print_r($list);
?>
Output
Array
(
[0] => apple
[1] => banana
[2] => cling
[3] => soon
[4] => 31
[5] => 32
)
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
