PHP: Is an array empty?

In the PHP language, it is a common operation to determine whether an array is empty. PHP provides a variety of methods to determine whether an array is empty, the simplest of which is to use the empty() function and the count() function. This article will start with the basic use of these two functions and explore different ways to determine whether an array is empty.

empty() function

empty() The function determines whether a variable is empty. Specifically, the empty() function returns true when the variable meets one of the following conditions:

• The variable is null
• This variable is an empty string ('')
• This variable is 0 or '0'
• This variable is false
• This variable is an empty array

Therefore, when an array is empty, you can use empty () Function judgment. The following is a sample code to determine whether an array is empty:

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

In the above code, an empty array array() is initially defined, and the empty() function is used to determine Whether the array is empty and output the corresponding information. The result shows: "The array is empty".

count() function

count() function is used to count the number of elements in an array. When an array is empty, the count() function returns 0. Therefore, you can also use the count() function to determine whether an array is empty. The following is an example code that uses the count() function to determine whether the array is empty:

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

In the above code, an empty array array() is initially defined, using count()The function calculates the number of elements in the array and determines whether it is 0, and outputs the corresponding information. The result shows: "The array is empty".

is_array() function

Another way to determine whether a variable is an array is to use the is_array() function. This function will determine whether the incoming variable is an array, and if so, it will return true, otherwise it will return false. Therefore, you can also use the is_array() function to determine whether an array is empty. The following is an example code that uses the is_array() function to determine whether the array is empty:

$array = array();
if (is_array($array) && empty($array)) {
    echo "该数组为空";
} else {
    echo "该数组不为空";
}

In the above code, an empty array array() is initially defined, using # The ##is_array() function determines whether the variable is an array, and uses the empty() function to determine whether the array is empty and outputs the corresponding information. The result shows: "The array is empty".

array_key_exists() function

array_key_exists()The function is used to check whether the given key name or index exists in the array. If present, returns true, otherwise returns false. When an array is empty, you can use the array_key_exists() function to determine. The following is a sample code to determine whether an array is empty:

$array = array();
if (!array_key_exists(0, $array)) {
    echo "该数组为空";
} else {
    echo "该数组不为空";
}

In the above code, an empty array

array() is initially defined, and the array_key_exists() function is used to determine Whether the element with index 0 in the array exists and output the corresponding information. The result shows: "The array is empty".

Summary

Determining whether an array is empty is a basic operation in the PHP language. The above introduces several common methods in the PHP language, including the

empty() function and count() function, etc. Different methods have their own characteristics and usage scenarios. Users can use appropriate methods to judge and process arrays according to specific situations. For in-depth knowledge about PHP, please refer to the relevant documentation and tutorials.

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