PHP determines whether the obtained array is empty

As a server-side scripting language, PHP is very convenient for array processing. But during use, we often need to determine whether an array is empty. Let's introduce how to determine whether the obtained array is empty.

The simplest way is to use the empty() function, as shown below:

<?php
$arr1 = array();
$arr2 = array(null);

if(empty($arr1)) {
    echo "arr1为空
";  // 输出arr1为空
}

if(empty($arr2)) {
    echo "arr2为空
";  // 输出arr2为空
}
?>

In this example, $arr1 is an empty array, and $arr2 is an array with only one element being null. array. Use the empty() function to determine whether it is empty. The output results of both arrays are "empty".

Note that you can use the empty() function to determine whether a variable is empty, not just an array. When the variable value is 0, false, empty string, empty array, null, or undefined variable, the empty() function will return true.

Another way is to use the count() function, as shown below:

<?php
$arr1 = array();
$arr2 = array(null);

if(count($arr1) == 0) {
    echo "arr1为空
";  // 输出arr1为空
}

if(count($arr2) == 0) {
    echo "arr2为空
";  // 输出arr2为空
}
?>

Use the count() function to determine whether the array is empty by comparing the number of array elements with 0. Different from the empty() function, the count() function will not judge 0, false, empty string, etc. as an empty array. It will return true only when the number of array elements is 0.

Finally, we can also use the array_key_exists() function to determine whether the array is empty, as shown below:

<?php
$arr1 = array();
$arr2 = array(null);

if(!array_key_exists(0, $arr1)) {
    echo "arr1为空
";  // 输出arr1为空
}

if(!array_key_exists(0, $arr2)) {
    echo "arr2为空
";  // 输出arr2为空
}
?>

Use the array_key_exists() function to determine whether there is a specified key value in the array. If the array does not have any elements, or all key values ​​in the array are not equal to the specified key value, then the array is judged to be empty and "empty" is output.

To sum up, there are three ways for PHP to determine whether the obtained array is empty, namely using the empty() function, count() function and array_key_exists() function. It is recommended to choose flexibly according to your own needs in actual programming.

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