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

In PHP development, we often use arrays to store some data. However, sometimes there will be some empty values ​​in the array. If these empty values ​​are not handled, it will affect the correctness of the program when we operate on the array. Therefore, in some scenarios, we need to filter null values ​​in the array. This article will introduce how to use PHP to remove empty values ​​from an array.

1. What is an array

In PHP, an array is a special data type used to store a set of ordered data. Each element of the array has a unique subscript, and the elements in the array can be accessed through the subscript. The subscript can be an integer or a string.

For example, the following is the definition of an array:

$fruits = array("apple", "banana", "orange");

In this array, the subscripts of each element are 0, 1, and 2 respectively. We can get the elements in the array through subscripts, for example:

echo $fruits[0]; // 输出"apple"
echo $fruits[1]; // 输出"banana"
echo $fruits[2]; // 输出"orange"

2. Null values ​​in the array

The null value in the array refers to the elements that have not been assigned a value, or have been assigned a value The element that is null. For example, the following is an array containing null values:

$arr = array("apple", null, "banana", "", "orange");

In this array, the second element is null and the fourth element is the empty string. If these null values ​​are not handled, they may cause a lot of unnecessary trouble in the program.

3. Remove null values ​​from arrays

PHP provides some functions that can be used to remove null values ​​from arrays. Here are some commonly used functions:

1. array_filter() function

array_filter() function can be used to filter elements in an array. Its first parameter is the array that needs to be filtered, and the second parameter is a callback function used to specify the filtering conditions. The callback function receives an array element as a parameter. If the return value is true, it means that the element needs to be retained, otherwise it will be filtered out.

Using the array_filter() function can easily remove the null values ​​​​in the array, for example:

$arr = array("apple", null, "banana", "", "orange");
$arr = array_filter($arr);

print_r($arr); // 输出Array ( [0] => apple [2] => banana [4] => orange )

In this example, the array_filter() function is used to filter the null values ​​​​of the original array, retaining a non-null value. Note that the indexes of the filtered array will be rearranged, so the original indexes may change.

2. array_diff() function

array_diff() function can be used to calculate the difference set of arrays. It takes two or more arrays as arguments and returns a new array consisting of elements of the first array that are different from the remaining arrays.

Use the array_diff() function to remove null values ​​​​in the array, for example:

$arr = array("apple", null, "banana", "", "orange");
$arr = array_diff($arr, array(null, ""));

print_r($arr); // 输出Array ( [0] => apple [2] => banana [4] => orange )

In this example, the array_diff() function is used to calculate the original array and an array containing only null values. The difference set of , we get a new array without null values.

3. foreach loop

In addition to using the functions provided by PHP, we can also use the foreach loop to traverse the array and manually remove the null values ​​​​in it.

For example, the following code uses a foreach loop to traverse the array and remove the null values:

$arr = array("apple", null, "banana", "", "orange");
$newArr = array();

foreach ($arr as $value) {
    if ($value !== null && $value !== "") {
        $newArr[] = $value;
    }
}

print_r($newArr); // 输出Array ( [0] => apple [2] => banana [4] => orange )

In this example, an empty array $newArr is first defined to store the null values. the new array after. Then use a foreach loop to iterate through each element of the original array, and if the element is not null or an empty string, add it to the new array. Finally, output the new array.

4. Summary

This article introduces how to use PHP to remove null values ​​​​in an array. In general, we can use the array_filter() function, array_diff() function provided by PHP, or manually use a foreach loop to remove null values ​​​​in the array. In actual development, which method to use can be freely chosen according to specific scenarios.

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