How to use PHP array sorting function_PHP tutorial
WBOYOriginal
2016-07-13 10:48:07831browse
There are many data sorting functions in PHP, including one-dimensional array sorting functions and two-dimensional array sorting functions, including simple sort function ascending sorting, rsort descending order, etc.
PHP array sorting functions include
sort ( &$arr [,fruits] ) Sort the array from low to high and assign a new key name. Return bool
rsort ( &$arr [,fruits] ) Reverse sort the array and assign new key names
asort ( &$arr [,fruits] ) sorts the array, keeping the index unchanged
arsort( &$arr [,fruits] ) sorts the array in reverse order and keeps the index unchanged
ksort ( &$arr [,fruits] ) sorts the array by key name
krsort( &$arr [,fruits] ) sorts the group numbers in reverse order by key name
natsort( &$arr ) Performs ‘natural sorting’ on array key values, sorting by length, alphabet, etc.
natcasesort( &$arr ) performs case-insensitive ‘natural ranking’ of arrays
usort ( &$arr , cmp_function ) User-defined function sorts an array and rearranges key names
uksort (&$arr, cmp_function) User-defined function sorts an array by key name
uasort (&$arr, cmp_function) user-defined function sorts the array and keeps the index unchanged
array_multisort( $arr , mixed)
The second parameter can change the sorting behavior based on the value
SORT_REGULAR Normal comparison unit SORT_NUMERIC unit is compared as a number
SORT_STRING cells are compared as strings SROT_LOCALE_STRING cells are compared as strings according to the current local settings
--------------------sort function ascending order----------------------------- ------
bool sort ( array &$array [, int $sort_flags= SORT_REGULAR ] )
// Sort and print the resulting array
uasort($array, 'cmp');
var_dump($array);
?>
结果：
array
'a' =>
int
4
'b' =>
int
8
'c' =>
int
-1
'd' =>
int
-9
'e' =>
int
2
'f' =>
int
5
'g' =>
int
3
'h' =>
int
-4
array
'd' =>
int
-9
'h' =>
int
-4
'c' =>
int
-1
'e' =>
int
2
'g' =>
int
3
'a' =>
int
4
'f' =>
int
5
'b' =>
int
8
var_dump($a);
?>
Result:
array
0 =>
int
1
1 =>
int
2
2 =>
int
3
3 =>
int
5
4 =>
int
6
-----------------uksort uses a custom function to sort the array by key-----------------
The code is as follows
Copy code
function cmp($a, $b)
{
$a = preg_replace('@^(a|an|the) @', '', $a);
$b = preg_replace('@^(a|an|the) @', '', $b);
Return strcasecmp($a, $b);
}<🎜>
<🎜>$a = array("John" => 1, "the Earth" => 2, "an apple" => 3, "a banana" => 4);
uksort($a, "cmp");
var_dump($a);
?>
Result:
array
'an apple' =>
int
3
'a banana' =>
int
4
'the Earth' =>
int
2
'John' =>
int
1
------------------uasort uses a custom function to sort the array by value, keeping the index relationship unchanged---------
The code is as follows
Copy code
// Comparison function
function cmp($a, $b) {
If ($a == $b) {
return 0;
}
Return ($a < $b) ? -1 : 1;
}<🎜>
<🎜>// Array to be sorted
$array = array('a' => 4, 'b' => 8, 'c' => -1, 'd' => -9, 'e' => 2, 'f' => 5, 'g' => 3, 'h' => -4);
var_dump($array);
// Sort and print the resulting array
uasort($array, 'cmp');
var_dump($array);
?>
Result:
array
'a' =>
int
4
'b' =>
int
8
'c' =>
int
-1
'd' =>
int
-9
'e' =>
int
2
'f' =>
int
5
'g' =>
int
3
'h' =>
int
-4
array
'd' =>
int
-9
'h' =>
int
-4
'c' =>
int
-1
'e' =>
int
2
'g' =>
int
3
'a' =>
int
4
'f' =>
int
5
'b' =>
int
8
------------------array_multisort Sort multiple arrays or multidimensional arrays---------
string
'a' (length=1)
1 =>
array
0 =>
int
1
1 =>
int
3
2 =>
string
'2' (length=1)
3 =>
int
2
4 =>
int
1
//Description:
1 In the above example: the $ar array is first arranged in ascending order according to the string value of $ar[0]. If the string values are equal, it is then arranged in descending order according to the numeric value of the $ar[1] array.
2. If the parameter at any position of the array_multisort function is an array, it indicates the value used for sorting,
If there are multiple array parameters, the previous array value will be sorted first. If it is a constant, such as
SORT_ASC, SORT_DESC, SORT_REGULAR,SORT_NUMERIC, SORT_STRING.
PHP two-dimensional array sorting function
You can use sort(), asort(), arsort() and other functions to sort PHP one-dimensional arrays, but the sorting of PHP two-dimensional arrays needs to be customized.
The following function sorts a given two-dimensional array according to the specified key value. Let’s look at the function definition first:
The code is as follows
Copy code
function array_sort($arr,$keys,$type='asc'){
$keysvalue = $new_array = array();
foreach ($arr as $k=>$v){
$keysvalue[$k] = $v[$keys];
}
if($type == 'asc'){
asort($keysvalue);
}else{
arsort($keysvalue);
}
reset($keysvalue);
foreach ($keysvalue as $k=>$v){
$new_array[$k] = $arr[$k];
}
return $new_array;
}
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