PHP determines whether array is empty

In PHP development, determining whether an array is empty is a common problem. Because when processing data, we often need to operate on arrays, and if the array is empty, an error may occur in the program. So, what methods are there in PHP to determine whether an array is empty? This article will introduce this in detail.

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

There is a function in PHP specifically used to determine whether a variable is empty-empty(). The function of this function is to determine whether the specified variable is empty or whether there are elements in the array. If empty, returns true, otherwise returns false. We can use the empty() function to determine whether the array is empty.

Sample code:

<?php
$data = array();
if(empty($data)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}
?>

In the above code, we first create an empty array $data, and then use the empty() function to determine whether the array is empty. Since the array is empty, "array is empty" is output.

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

In addition to the empty() function, PHP also provides a function to obtain the number of array elements - the count() function. The return value of this function is an integer, indicating the number of elements in the array. If the return value is 0, it means that the array is empty.

Sample code:

<?php
$data = array();
if(count($data) == 0) {
    echo "数组为空";
} else {
    echo "数组不为空";
}
?>

In the above code, we also create an empty array $data, and then use the count() function to get the number of elements in the array. Since the array is empty, the number of elements is 0, and "array is empty" is output.

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

In addition to the empty() and count() functions, PHP also provides a function to determine whether the variable is set - isset() function. The function of this function is to determine whether a variable has been set and is not NULL. For arrays, if there are no elements in the array, the array is considered unset.

Sample code:

<?php
$data = array();
if(!isset($data[0])) {
    echo "数组为空";
} else {
    echo "数组不为空";
}
?>

In the above code, we also create an empty array $data, and then use the isset() function to determine whether the first element of the array has been set. Since the array is empty, the first element does not exist, and "array is empty" is output.

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

PHP also provides a function to check whether the specified key name exists in the array-array_key_exists() function. Returns true if the specified key exists in the array, otherwise returns false. If we want to determine whether an array is empty, we can use this function to determine whether the first element of the array exists.

Sample code:

<?php
$data = array();
if(!array_key_exists(0, $data)) {
    echo "数组为空";
} else {
    echo "数组不为空";
}
?>

In the above code, we also create an empty array $data, and then use the array_key_exists() function to determine whether the first element of the array exists. Since the array is empty, the first element does not exist, and "array is empty" is output.

5. Summary

The above are the four ways to determine whether an array is empty in PHP. No matter which method is used, as long as the judgment result is true, it means that the array is empty; otherwise, it means that the array is not empty. In actual development, according to different needs, we can choose a method that suits us to determine whether an array is empty.

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