How to remove empty values ​​from an array in php

In PHP, array is a very common and important data type. As a PHP developer, we often need to operate and process arrays. In some cases, there may be some null values ​​(NULL) or empty strings in the array. These values ​​are meaningless and may also affect our code logic and program performance. Therefore, this article will introduce how to remove empty values ​​​​in an array.

1. What is a null value?

In PHP, a null value (NULL) refers to a variable that has no value or a variable that is explicitly set to NULL. Additionally, the empty string ('') can also be considered a null value because it is a string of length 0.

2. Remove null values ​​from the array

In PHP, there are many ways to remove null values ​​from the array. Below we list several commonly used methods:

1. Use the array_filter function

The array_filter function can filter elements in an array. Its usage is as follows:

array_filter($array)

Among them, $array is the array to be filtered. This function returns a new array that does not contain null values.

Sample code:

$array = array('a', 'b', '', 'c', NULL, 'd', '', 'e', 'f');
$new_array = array_filter($array);
print_r($new_array);

The output result of the above code is as follows:

Array
(
    [0] => a
    [1] => b
    [3] => c
    [5] => d
    [7] => e
    [8] => f
)

2. Use foreach loop

Use foreach loop to traverse the array and convert the non-empty Just put the elements into a new array.

Sample code:

$array = array('a', 'b', '', 'c', NULL, 'd', '', 'e', 'f');
$new_array = array();
foreach ($array as $value) {
    if (!empty($value)) {
        $new_array[] = $value;
    }
}
print_r($new_array);

The output of the above code is the same as above.

3. Use the array_map function

The array_map function can apply a callback function to each element in the array. We can set up a callback function that replaces null values ​​with a default value and returns a new array.

Sample code:

function replace_empty($value) {
    return $value === '' || $value === NULL ? 'default' : $value;
}

$array = array('a', 'b', '', 'c', NULL, 'd', '', 'e', 'f');
$new_array = array_map('replace_empty', $array);
print_r($new_array);

The output of the above code is as follows:

Array
(
    [0] => a
    [1] => b
    [2] => default
    [3] => c
    [4] => default
    [5] => d
    [6] => default
    [7] => e
    [8] => f
)

3. Summary

This article introduces how to remove null values ​​​​in PHP arrays. These include three methods using the array_filter function, foreach loop and array_map function. These methods are techniques often used by PHP programmers in their work, and they can effectively improve the performance and readability of the program. When we process some large data, it is best to remove the null values ​​​​in the array to reduce the size of the array and improve the efficiency of the program.

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