Home > Article > Backend Development > Collection of PHP array sorting functions and analysis of the connections between them_PHP Tutorial

Collection of PHP array sorting functions and analysis of the connections between them_PHP Tutorial

WBOYOriginal: 2016-07-21 15:03:16757browse

The sorting of several array functions mentioned below have some commonalities:
1 The array is used as a parameter of the sorting function. After sorting, the array itself changes. The function The return value is of bool type.
2 The single a appearing in the function name means association, which means that in the process of sorting by value, the corresponding relationship of key=>value remains unchanged
3 The single k appearing in the function name means key, which means: , in the process of sorting by value, sort according to the array key instead of the value of the array
4 The single r appearing in the function name means reverse, which means that the order is in the opposite order of not adding r
5 Function name The single u appearing in means user-defined, which means that the user-defined function is used to sort. If the logic of the function is that parameter 1 < parameter 2 returns a negative number, then the order is in ascending order (p1 is smaller than 2 and returns negative and ascending).
--------------------sort function ascending order-------------------- ------------

Copy code The code is as follows:

bool sort ( array &$array [, int $sort_flags= SORT_REGULAR ] )
$fruits = array("lemon", "orange", "banana", "apple");
sort( $fruits);
var_dump($fruits);
?>
Result:
array
0 =>
string
'apple' (length=5)
1 =>
string
'banana' (length=6)
2 =>
string
'lemon' (length=5)
3 => ;
string
'orange' (length=6)

------------------------rsort descending order Arrangement--------------------

Copy code The code is as follows:

$fruits = array("lemon", "orange", "banana", "apple");
rsort($fruits);
var_dump($ fruits);
?>
Result: 
array
 0 => 
string
 'orange' (length=6)
 1 => string
 'lemon' (length=5)
 2 => 
string
 'banana' (length=6)
 3 => 
string
 'apple ' (length=5)

---------------asort is arranged in ascending order of the two-dimensional array values (keeping key=>value Association) -----------

Copy code The code is as follows:

< ;?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple" );
asort($fruits);
var_dump($fruits);
?>
Result: 
array
 'c' => 
string
 'apple' (length=5)
 'b' => 
string
 'banana' (length=6)
 'd' => 
string
 ' lemon' (length=5)
 'a' => 
string
 'orange' (length=6)

------ --arsort is arranged in descending order of the two-dimensional array values (maintaining the association of key=>value) ---------

Copy code The code is as follows:

$fruits = array("d" => "lemon", "a" => "orange", "b " => "banana", "c" => "apple");
arsort($fruits);
var_dump($fruits);
?>
result
 array
 'a' => 
string
 'orange' (length=6)
 'd' => 🎜> 'b' => 
string
 'banana' (length=6)
 'c' => 
string
 'apple' (length=5)
 


--------------------ksort sorts the array in ascending order of keys---------------- 

Copy code

The code is as follows:$fruits = array("d" =>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");

ksort($fruits);

 var_dump($fruits);
?>
result
array
'a' => 
string
 'orange' (length=6)
 'b' => 
string
 'banana' (length=6)
 'c' => 
string
 'apple' (length=5)
 'd' => ; 
string
 'lemon' (length=5)
 


------------------------krsort Arrange in descending order of array key-----------------------

Copy code

The code is as follows:

$fruits = array("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c "=>"apple");
krsort($fruits);
var_dump($fruits);
?>
array
 'd' => 
string 
 'lemon' (length=5)
 'c' => 
string
 'apple' (length=5)
 'b' => 
string
 'banana' (length=6)
 'a' => 
string
 'orange' (length=6)
 

----- ----------usort function sorts according to user-defined functions----------------

Copy code The code is as follows:

function cmp($a, $b)
{
 if ($a == $b) {
 return 0;
 }
 return ($a < $b) ? -1 : 1;
}
$a = array(3, 2, 5, 6, 1);
usort($a, "cmp");
var_dump($a);
?>

Result:
array
0 =>
int
1
1 =>
int
2
2 =>
int
5
4 =>
int
6

-----------------uksort use custom The function is sorted by the key of the array-----------------

Copy code

The code is as follows: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----- ----

Copy code

The code is as follows:// 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---------

Copy code

The code is as follows:$ar = array(

array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);

array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC) ;
var_dump($ar);
?>

Result:
array
0 =>
array
0 =>
string
'10' (length=2)
1 =>
int
100
2 =>
int
100
3 =>
int
11
4 =>
string
'a' (length=1)
1 =>
array
0 =>
int
1
1 =>
int
3
2 =>
string
'2' (length=1)
3 =>
int
2
4 =>
int
1
//Explanation:
1 In the above example: the $ar array is first sorted in ascending order according to the string value of $ar[0]. If the string values are equal, then the numbers in the $ar[1] array are sorted. Values are sorted in descending order.
2 If the parameter at any position of the array_multisort function is an array, it represents 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.
indicates the sorting method (array values are taken first).
================================================== ===========================================
PHP Two-dimensional array sorting function
PHP one-dimensional array can be sorted using functions such as sort(), asort(), arsort(), etc., but the sorting of PHP two-dimensional array 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:

Copy the code The code is as follows:

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;
}

It can sort the two-dimensional array according to the specified key value, You can also specify ascending or descending order (default is ascending order), usage example:

Copy code The code is as follows:

$ array = array(
array('name'=>'Mobile phone','brand'=>'Nokia','price'=>1050),
array('name'=>' laptop','brand'=>'lenovo','price'=>4300),
array('name'=>'razor','brand'=>'Philips', 'price'=>3100),
array('name'=>'Treadmill','brand'=>'Sanwa Soushi','price'=>4900),
array ('name'=>'Watch','brand'=>'Casio','price'=>960),
array('name'=>'LCD TV','brand'= >'Sony','price'=>6299),
array('name'=>'Laser Printer','brand'=>'HP','price'=>1200)
);
$ShoppingList = array_sort($array,'price');
print_r($ShoppingList);

The above is the two-dimensional array of $array according to 'price' 'Sort from low to high.
Output result: (omitted).

Statement：

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Previous article：How to parse system information in php_PHP tutorialNext article：How to parse system information in php_PHP tutorial

See more

Collection of PHP array sorting functions and analysis of the connections between them_PHP Tutorial

Related articles