How to determine if an array is empty in php

With the widespread use of PHP, we sometimes encounter situations where we need to determine whether an array is empty. But how to correctly judge an empty array?

The most intuitive method is to use the count() function to count the number of array elements. If the number is 0, the array is empty. For example:

$arr = [];
if (count($arr) == 0) {
  echo '数组为空';
} else {
  echo '数组不为空';
}

The advantage of this method is that it is suitable for all types of arrays and is very simple and easy to understand. However, it also has some disadvantages. First of all, it takes up certain system resources and is not suitable for non-array type variables. Secondly, it cannot distinguish whether the array element is an empty string, an empty array, 0 or false, etc., so it may bring us some unexpected problems.

So, is there a better way to determine whether the array is empty? The answer is yes. Two commonly used methods are introduced below.

Use the empty() function

PHP provides the empty() function, which can directly determine whether a variable is empty without occupying system resources. For arrays, if the array does not contain any elements, it returns true directly, otherwise it returns false. For example:

$arr = [];
if (empty($arr)) {
  echo '数组为空';
} else {
  echo '数组不为空';
}

It should be noted that the empty() function only applies to variables, so the array must be assigned to a variable first and then judged. In addition, for arrays, the empty() function cannot distinguish between empty strings, 0 or false, etc., which are the same as empty arrays, so it needs to be used with caution.

Use the is_array() function

The is_array() function can determine whether a variable is an array type. It differentiates well between arrays and other types of variables without tying up system resources. Returns true if the variable is of array type, false otherwise. For example:

$arr = [];
if (is_array($arr) && count($arr) == 0) {
  echo '数组为空';
} else {
  echo '数组不为空';
}

It should be noted that you need to use the && operator combined with the count() function to ensure that the array is empty. Otherwise, if the variable is not of array type, the count() function will report an error.

To sum up, it is not too complicated to judge whether the array is empty, but it needs to be used selectively according to the actual situation. If the array type can be determined and does not need to be distinguished as an empty string, 0 or false, etc., you can use the is_array() function; otherwise, it is recommended to use the empty() function for judgment.

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