php determines whether it is an empty array

There are many ways to determine whether an array is empty in PHP. This article will introduce several methods to determine whether an array is empty.

[Method 1] count() function

count() function is used to count the number of array elements. When the array is empty, the return value is 0. Using this feature, you can Use the count() function to determine whether an array is empty. We can use the following code to determine whether an array is empty:

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

When the array is empty, "array is empty" will be output, otherwise "array is not empty" will be output.

[Method 2] empty() function

empty() function is used to check whether a variable is empty or 0. In PHP, if a variable is 0, empty string, or null , false or an empty array will be judged as "empty". Therefore, we can use the empty() function to judge whether an array is empty. The usage method is as follows:

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

When the array is empty, Output "array is empty", otherwise it will output "array is not empty".

[Method 3] isset() function

isset() function is used to detect whether the variable has been set and is not null. We can use the isset() function to determine whether an array is empty. The usage is as follows:

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

When the array is empty, "array is empty" will be output, otherwise "array is not empty" will be output.

[Method 4]array_key_exists() function

array_key_exists() function is used to determine whether a specified key exists in the array. We can use the array_key_exists() function to determine whether an array is Empty, the usage method is as follows:

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

When the array is empty, "array is empty" will be output, otherwise "array is not empty" will be output.

[Method 5] array_filter() function

array_filter() function is used to filter the elements in the array and only retain elements that meet the conditions. If the filtered array is empty, then the original array It is an empty array. We can use the array_filter() function to determine whether an array is empty. The method of use is as follows:

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

When the array is empty, "array is empty" will be output, otherwise "array" will be output. not null".

In actual development, we can choose different methods to determine whether an array is empty according to the specific situation. No matter which method is used, as long as it can correctly determine whether the array is empty.

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