To delete elements in PHP array, you need to select the method according to the scene. 1. Use unset() to delete elements of the specified key, which is suitable for the known key name, but will not be re-indexed; 2. Use array_diff() to delete by value, and the same value can be deleted in batches, which is slightly less efficient; 3. array_diff_key() can be deleted by differential key name; 4. array_filter() supports custom logical filtering and deletion, which is highly flexible; 5. array_splice() can be deleted by position and quantity, and automatically re-arranged indexes. Different methods are suitable for different requirements, pay attention to the processing and performance impact of keys.

Deleting elements in PHP arrays is actually a very common operation. The key is to choose the appropriate method according to the specific situation. The following practices can basically cover most usage scenarios.

Use the unset() function to delete elements of the specified key

unset() is the most straightforward way, suitable for use when you know the key of the element you want to delete. for example:

 $arr = ['a', 'b', 'c'];
unset($arr[1]);

After execution, 'b' with index 1 is deleted. However, be aware that this method will not re-index the array. If you need continuous numeric indexes, you can manually call array_values() to rearrange the indexes later.

• If it is an associative array, such as 'name' => 'John' , it is more intuitive to use unset($arr['name']) .
• It is not recommended to use unset() to delete the current element when traversing the array, as errors are prone to occur.

Use array_diff() or array_diff_key() to filter and delete

If you want to delete elements based on the value, instead of keys, you can use array_diff() . It compares the values ??of the array and returns the difference set. For example:

 $arr = ['a', 'b', 'c'];
$arr = array_diff($arr, ['b']);

In this way, all elements with a value of 'b' will be deleted. The advantage of this method is that it can delete multiple identical values ??in batches, but the cost is that it is slightly less efficient, especially when it comes to large arrays.

If you are deleting the key, use array_diff_key() to pass in the key name you want to exclude.

Use array_filter() to customize the deletion logic

array_filter() comes in handy when you want to delete elements that meet certain conditions. For example, only numbers greater than 10 are retained:

 $filtered = array_filter($numbers, function($val) {
    return $val > 10;
});

You can also write more complex judgment logic in it, which is very flexible. By default, array_filter() will retain the original key. If it is not necessary, you can pass ARRAY_FILTER_USE_BOTH in the second parameter or call array_values() afterwards.

Tips: Don't forget array_splice()

Although not commonly used, array_splice() can also be used to delete elements, especially when you want to slice and delete by position and quantity. For example, start with the second element and delete two:

 array_splice($arr, 1, 2);

This method will also automatically re-index, suitable for processing numerical index arrays.

Basically, these are the methods, which one to choose depends on the specific needs. Some seemingly simple places, such as whether the keys are retained and whether they need to be reindexed, are actually easy to ignore, but they will affect the subsequent processing logic.

The above is the detailed content of How to remove element from php array. For more information, please follow other related articles on the PHP Chinese website!