How to determine whether an array in php

Is empty?

In PHP, array is a very commonly used data structure. In daily development, we often need to determine whether an array is empty. Therefore, this article will introduce how to use PHP to determine whether an array is empty.

1. What is an empty array?

In PHP, an array is considered empty when all of the following conditions are met:

1. The length of the array is 0
2. All elements of the array are empty Value (for example: NULL, empty string, empty array, etc.).

If an array meets any of the above conditions, it is considered an empty array.

2. Use the empty function to determine whether the array is empty

The empty function is a very convenient function that can be used to determine whether any variable is empty. For arrays, we can use the empty() function to determine whether the array is empty. If the array is empty, the return value of this function is true, otherwise it returns false. For example:

$arr1 = array();
$arr2 = array(1, 2, 3);

if (empty($arr1)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

if (empty($arr2)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

The output result is:

数组为空
数组不为空

3. Use the count function to determine whether the array is empty

The count() function is used to return the number of elements in the array. When an array has no elements, its length is 0. Therefore, we can use the count() function to determine whether an array is empty. For example:

$arr1 = array();
$arr2 = array(1, 2, 3);

if (count($arr1) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

if (count($arr2) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

The output result is:

数组为空
数组不为空

4. Use the array_filter function to determine whether the array is empty

array_filter() function is used to filter all empty elements in the array. All non-empty elements are reassembled into a new array and returned. If there are no elements in the array, an empty array is returned. Therefore, we can use the array_filter() function to determine whether an array is empty. For example:

$arr1 = array();
$arr2 = array(1, 2, 3);

if (empty(array_filter($arr1))) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

if (empty(array_filter($arr2))) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

The output result is:

数组为空
数组不为空

5. Use the isset function to determine whether the array is empty

isset() function is used to check whether a variable has been set, and Not null. When all elements in the array are not set, it is considered an empty array. Therefore, we can use the isset() function to determine whether an array is empty. For example:

$arr1 = array();
$arr2 = array(1, 2, 3);

if (isset($arr1) && count($arr1) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

if (isset($arr2) && count($arr2) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}

The output result is:

数组为空
数组不为空

6. Summary

This article introduces several commonly used methods to determine whether an array is empty. It is recommended that in actual development, the most suitable method be selected according to the specific situation. At the same time, for the readability and maintainability of the code, it is recommended to add necessary comments to the code.

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