How to remove null values ​​from array in php

PHP is a widely used server-side scripting language. During the development process, we often need to process various data, among which arrays are a widely used data type. Sometimes, we need to remove null values ​​​​in an array for subsequent operations. This article will introduce how to remove null values ​​​​from an array in PHP.

1. What is an array null value?

In PHP, the null value in an array refers to the following value:

1. null
2. false
3. 0
4. 0.0
5. ""
6. Empty array

For the above values, all are considered in the array is a null value.

2. Method of removing null values ​​from the array

1. unset function

You can use PHP’s unset() function to delete the specified variables in the array . When we delete a variable from an array, the variable is completely deleted, not just assigned a null value.

The following is the code that uses the unset() function to delete null values ​​​​in the array:

<?php
$arr = array(&#39;apple&#39;, &#39;&#39;, &#39;banana&#39;, null, &#39;pear&#39;);
foreach ($arr as $key => $value) {
    if (empty($value)) {
        unset($arr[$key]);
    }
}
print_r($arr);
?>

输出：Array ( [0] => apple [2] => banana [4] => pear )

The above code uses a foreach loop to traverse each element in the array. If the value is null, then Use the unset() function to remove elements from an array. Finally, the array contents after deleting null values ​​are output through the print_r() function.

It should be noted that when using a foreach loop to traverse an array, try not to modify the array as much as possible. Otherwise, incomplete traversal may occur.

2. array_filter function

PHP’s array_filter() function can delete null values ​​​​in the array.

The following is the code that uses the array_filter() function to delete null values ​​​​in the array:

<?php
$arr = array(&#39;apple&#39;, &#39;&#39;, &#39;banana&#39;, null, &#39;pear&#39;);
$arr = array_filter($arr, &#39;strlen&#39;); //使用strlen函数删除空值
print_r($arr);
?>

输出：Array ( [0] => apple [2] => banana [4] => pear )

The above code uses the array_filter() function to filter the null values ​​​​in the array, and uses the strlen() function As a filter condition, delete elements with a string length of 0.

It should be noted that the array_filter() function will delete elements with a value equal to false by default.

3. array_diff function

PHP’s array_diff() function can be used to compare two arrays and return the difference. This method can be used to remove null values ​​from an array.

The following is the code that uses the array_diff() function to delete null values ​​​​in the array:

<?php
$arr = array(&#39;apple&#39;, &#39;&#39;, &#39;banana&#39;, null, &#39;pear&#39;);
$arr = array_diff($arr, array(&#39;&#39;)); //删除数组中为空的元素
print_r($arr);
?>

输出：Array ( [0] => apple [2] => banana [4] => pear )

The above code uses the array_diff() function to compare the $arr array and an array containing only null values. Assign the result to $arr, thereby removing the null elements in the $arr array.

4. Summary

The above are several methods to remove null values ​​​​from arrays in PHP. Different methods can be selected and used according to the specific situation. It should be noted that when operating in an array, you must pay attention to traversing and modifying the array to avoid incomplete traversal problems as much as possible.

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