分享六個比較好用的php數組Array函數

2024-05-05 00:04:32

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1. array_column 返回輸入數組中某個單一列的值。
2. array_filter 用回調函數過濾數組中的元素。
3. array_map 將用戶自定義函數作用到給定數組的每個值上，返回新的值。
4. array_walk_recursive 對數組中的每個成員遞歸地應用用戶函數。
5. extract (從數組中將變量導入到當前的符號表), compact (創建一個包含變量名和它們的值的數組)
6. uasort 使用用戶自定義的比較函數對數組中的鍵值進行排序。

1. array_column 返回輸入數組中某個單一列的值。

類似功能有

1.1 Yii2 中的 ArrayHelper::index($array, 'id');

1.2 Yii2 中的 $query->select(['last_name', 'id'])->indexBy('id')->column();

// 可能從數據庫中返回數組$a = array( array(  'id' => 5698,  'first_name' => 'Peter',  'last_name' => 'Griffin', ), array(  'id' => 4767,  'first_name' => 'Ben',  'last_name' => 'Smith', ), array(  'id' => 3809,  'first_name' => 'Joe',  'last_name' => 'Doe', ));$last_names = array_column($a, 'last_name', 'id');print_r($last_names);

輸出結果:

Array
(
    [5698] => Griffin
    [4767] => Smith
    [3809] => Doe
)

2. array_filter 用回調函數過濾數組中的元素。

function test_odd($var){  return($var & 1);}$a1=array("a","b",2,3,4);print_r(array_filter($a1,"test_odd"));

輸出:

Array
(
    [2] => 2
    [3] => 3
    [4] => 4
)

3. array_map 將用戶自定義函數作用到給定數組的每個值上，返回新的值。

此函數有點類似與 array_walk_recursive , 只是多寫了一步遞歸

 function myfunction($v) {   if (is_array($v)) {     return array_map("myfunction", $v);   }  return($v * $v);}  $a = array(1, 2, 3, 4, 5, 6 => [2, 3]);print_r(array_map("myfunction", $a));

輸出:

Array
(
    [0] => 1
    [1] => 4
    [2] => 9
    [3] => 16
    [4] => 25
    [6] => Array
        (
            [0] => 4
            [1] => 9
        )

)

 function myfunction($v1, $v2) {  if ($v1 === $v2) {     return "same";   }   return "different"; }  $a1 = array("Horse", "Dog", "Cat"); $a2 = array("Cow", "Dog", "Rat"); print_r(array_map("myfunction", $a1, $a2));

輸出:

Array
(
    [0] => different
    [1] => same
    [2] => different

4. array_walk_recursive 對數組中的每個成員遞歸地應用用戶函數。

此函數有點類似與 array_map, 只是省去了寫遞歸

 function myfunction(&$value, $key, $p) {   if ($value == 'xxx') {     $value = $p;   } } $a = array("a" => "red", "b" => "green", "c" => "blue", 'd' => ['x' => 'xxx', 'y' => 'yyy']); array_walk_recursive($a, "myfunction", 'green'); print_r($a);

輸出:

Array
(
    [a] => red
    [b] => green
    [c] => blue
    [d] => Array
        (
            [x] => green
            [y] => yyy
        )

)

5. extract (從數組中將變量導入到當前的符號表), compact (創建一個包含變量名和它們的值的數組)

 $a = "Original";$my_array = array("a" => "Cat","b" => "Dog", "c" => "Horse"); extract($my_array); echo "/$a = $a; /$b = $b; /$c = $c";

輸出:

$a = Cat; $b = Dog; $c = Horse

 $firstname = "Peter"; $lastname = "Griffin"; $age = "41";$result = compact("firstname", "lastname", "age"); print_r($result);

輸出:

Array
(
    [firstname] => Peter
    [lastname] => Griffin
    [age] => 41
)

6. uasort 使用用戶自定義的比較函數對數組中的鍵值進行排序(可以對二維數組排序)。

$arr2 = [  [    'id' => 3,    'age' => 33,  ],  [    'id' => 2,    'age' => 44,  ],  [    'id' => 1,    'age' => 22,  ],];//按age字段升序排序uasort($arr2, function($a, $b) {  $field = 'age';  if ($a[$field] == $b[$field]){    return 0;  }  return ($a[$field] < $b[$field]) ? -1 : 1;});print_r($arr2);

輸出:

Array
(
    [2] => Array
        (
            [id] => 1
            [age] => 22
        )

    [0] => Array
        (
            [id] => 3
            [age] => 33
        )

    [1] => Array
        (
            [id] => 2
            [age] => 44
        )

)