PHP multi-dimensional array sorting, maintaining index correspondence, clever use of uasort_PHP tutorial

In actual development, you will more or less encounter array sorting problems. In addition to conventional simple sorting algorithms, PHP also provides built-in array sorting functions. This time we will focus on sharing: uasort uses user-defined comparison functions to sort arrays. Sort the values ​​and maintain the index association, which can sort multi-dimensional arrays. This article focuses on this function. ​​

uasort function

Parameter type: bool uasort (array &$array, callable $cmp_function)

This function sorts the array and maintains the association between index and cell.

Mainly used for sorting associative arrays where the order of units is important. The comparison function is user-defined.

Returns TRUE on success, or FALSE on failure.

Array sorting example (not in class):

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1 /**

2 * Custom sorting function

3 * @param $param1

4 * @param $param2

5 * @return 0 (no movement) 1 (forward swap sequence) -1 (reverse swap sequence)

6*/

7

8 function my_sort($param1, $param2){

9 if($param1 == $param2) return 0;

10 else return $param1 > $param2 ? 1 : -1;

11 }

12

13 $arr = array(

14           'a'=>'20',

15 'b'=>'1',

16 'c'=>'10',

17 'd'=>'5',

18 'e'=>'21',

19 'f'=>'4',

20           'g'=>'3',

21 );

22

23 uasort($arr, 'my_sort');

24

25 var_dump($arr);

26

27 /*Output value

28 array (size=7)

29 'b' => string '1' (length=1)

30 'g' => string '3' (length=1)

31 'f' => string '4' (length=1)

32 'd' => string '5' (length=1)

33 'c' => string '10' (length=2)

34 'a' => string '20' (length=2)

35 'e' => string '21' (length=2)

36 */

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Multidimensional array sorting example (not in class):

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/**

* Custom sorting function

* @param $param1

* @param $param2

* @return 0 (no movement) 1 (forward swap sequence) -1 (reverse swap sequence)

*/

function my_sort($param1, $param2){

if($param1['value'] == $param2['value']) return 0;

else return $param1['value'] > $param2['value'] ? 1 : -1;

}

$arr = array(

          'a'=>array('key'=>'Definition 1', 'value'=>'20'),

          'b'=>array('key'=>'Definition 2', 'value'=>'1'),

          'c'=>array('key'=>'Definition 3', 'value'=>'10'),

          'd'=>array('key'=>'definition 4', 'value'=>'5'),

          'e'=>array('key'=>'Definition 5', 'value'=>'21'),

          'f'=>array('key'=>'Definition 6', 'value'=>'4'),

          'g'=>array('key'=>'Definition 7', 'value'=>'3'),

);

uasort($arr, 'my_sort');

var_dump($arr);

/*输出值

array (size=7)

  'b' => 

    array (size=2)

      'key' => string '定义2' (length=7)

      'value' => string '1' (length=1)

  'g' => 

    array (size=2)

      'key' => string '定义7' (length=7)

      'value' => string '3' (length=1)

  'f' => 

    array (size=2)

      'key' => string '定义6' (length=7)

      'value' => string '4' (length=1)

  'd' => 

    array (size=2)

      'key' => string '定义4' (length=7)

      'value' => string '5' (length=1)

  'c' => 

    array (size=2)

      'key' => string '定义3' (length=7)

      'value' => string '10' (length=2)

  'a' => 

    array (size=2)

      'key' => string '定义1' (length=7)

      'value' => string '20' (length=2)

  'e' => 

    array (size=2)

      'key' => string '定义5' (length=7)

      'value' => string '21' (length=2)

*/

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class中排序，为了方便以二维数组为例：

 

uasort($arr1, array($this, 'public_my_sort'));

 

uasort($arr2, array('self', 'self_my_sort'));

 

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class myClassSort{

    

    /**

* Sorting main method

* @param $arr1 self static sorting

* @param $arr2 this sorting

* @return sorted array

*/

    public function main($arr1 = array(), $arr2 = array()){

    

        uasort($arr1, array($this, 'public_my_sort'));

        

        uasort($arr2, array('self', 'self_my_sort'));

        

        return array('arr1'=>$arr1, 'arr2'=>$arr2);

    

    }

    

    /**

* Custom sorting function

* @param $param1

* @param $param2

* @return 0 (no movement) 1 (forward swap sequence) -1 (reverse swap sequence)

*/

    private static function self_my_sort($param1, $param2){

        if($param1['value'] == $param2['value']) return 0;

        else return $param1['value'] > $param2['value'] ? 1 : -1;

    }

    

    

    //同上

    public function public_my_sort($param1, $param2){

        if($param1['value'] == $param2['value']) return 0;

        else return $param1['value'] > $param2['value'] ? 1 : -1;

    }

    

}

 

$arr = array(

            'a'=>array('key'=>'定义1', 'value'=>'20'),

            'b'=>array('key'=>'定义2', 'value'=>'1'),

            'c'=>array('key'=>'定义3', 'value'=>'10'),

          'd'=>array('key'=>'definition 4', 'value'=>'5'),

          'e'=>array('key'=>'Definition 5', 'value'=>'21'),

          'f'=>array('key'=>'Definition 6', 'value'=>'4'),

          'g'=>array('key'=>'Definition 7', 'value'=>'3'),

);

$myClassSort = new myClassSort();

var_dump($myClassSort->main($arr, $arr));

/*The output result is the same as the above example*/

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Similar function extension

array_multisort sorts multiple arrays or multi-dimensional arrays, but the final filling is still a specific one-dimensional array

arsort sorts the one-dimensional array in reverse order and maintains the index relationship, maintaining the index correspondence

asort sorts the one-dimensional array forward and maintains the index relationship, maintaining the index correspondence

krsort sorts the array in reverse order by key name, maintaining the index correspondence

ksort sorts the array forward by key name and maintains the index correspondence

natcasesort uses the "natural sorting" algorithm to sort one-dimensional arrays in a case-insensitive manner. It can be used to sort alphanumeric mixed situations in the array content and maintain index correspondence

natsort uses the "natural sorting" algorithm to sort one-dimensional arrays, distinguishing between uppercase and lowercase letters, and can be used to sort alphanumeric mixed situations in the array content, maintaining the index correspondence

rsort reversely sorts a one-dimensional array without maintaining index correspondence

sort sorts the one-dimensional array forward, without maintaining the index correspondence

uasort uses a user-defined comparison function to sort the values ​​in the array and maintain index association. It can sort multi-dimensional arrays. This article focuses on this function

uksort uses a user-defined comparison function to sort the keys in the array

usort uses a user-defined comparison function to sort the values ​​in the array without maintaining index association

http://www.bkjia.com/PHPjc/767108.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/767108.htmlTechArticleIn actual development, you will more or less encounter array sorting problems. In addition to writing simple sorting algorithms, PHP also provides built-in array sorting functions. This time I will focus on sharing: uas...