Detailed explanation of four PHP methods to delete array elements

There are four ways to write the word "fennel" in fennel beans, and there are four ways to delete elements from an array in PHP.

Delete an element and keep the original index unchanged

Use unset function, the example is as follows :

<?php
  $array = array(0 => "a", 1 => "b", 2 => "c");
  unset($array[1]);
        //↑ 你想删除的key
?>

Output:

Array (
    [0] => a
    [2] => c
)

Using unset does not change the original index of the array. If you plan to rearrange the index (so that the index starts from 0 and is continuous), you can use the array_values function:

$array = array_values($array);
/*
输出
array(2) {
 [0]=>
 string(1) "a"
 [1]=>
 string(1) "c"
}
*/

Delete an element without keeping the index

Use the array_splice function, the example is as follows:

<?php
  $array = array(0 => "a", 1 => "b", 2 => "c");
  array_splice($array, 1, 1);
            //↑ 你想删除的元素的Offset
?>

Output:

Array (
    [0] => a
    [1] => c
)

Delete multiple elements by value, keeping the index

Use the array_diff function, the example is as follows:

<?php
  $array = array(0 => "a", 1 => "b", 2 => "c");
  $array = array_diff($array, ["a", "c"]);
               //└────────┘→ 你想删除的数组元素值values
?>

Output:

Array (
    [1] => b
)

Similar to unset, array_diff will also keep the index.

Delete multiple elements by key, keeping the index

Use the array_diff_key function, the example is as follows:

<?php

  $array = array(0 => "a", 1 => "b", 2 => "c");
  $array = array_diff_key($array, [0 => "xy", "2" => "xy"]);
                  //↑      ↑ 你想删除的数组键keys
?>

Output:

Array (
    [1] => b
)

Similar to unset, array_diff_key will also maintain the index.

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