How to determine if an array is empty in php

In PHP, there are many ways to determine whether an empty array is present. This article will introduce you to these methods in detail.

Method 1: Use the count() function

The most common way to determine an empty array is to use the count() function. Determine whether an array is empty by counting the number of array elements. The specific implementation is as follows:

if (count($array) == 0) {
  // $array 是空数组
} else {
  // $array 不是空数组
}

This method is very simple and only needs to use a conditional statement to complete. However, it requires traversing the entire array to calculate the number of elements, so it may impact performance when working with large arrays.

Method 2: Use the empty() function

The empty() function can determine whether a variable is empty, including empty string, empty array, null and false. The specific implementation is as follows:

if (empty($array)) {
  // $array 是空数组
} else {
  // $array 不是空数组
}

This method is faster than the count() function because it does not need to traverse the entire array. However, it may consider elements containing false, 0, and "" in a non-empty array to be empty, so it is not suitable for all cases.

Method 3: Use the isset() function

isset() function can determine whether a variable exists and is not null. Therefore, if an array variable exists but has no elements, it is not an empty array. The specific implementation is as follows:

if (isset($array) && !empty($array)) {
  // $array 不是空数组
} else {
  // $array 是空数组
}

Note that you need to use the isset() function and the empty() function at the same time, because if you only use the isset() function to determine whether the array is empty, the empty array will also be judged to exist but not element.

Method 4: Use the array() function

Defining an empty array is also a way to determine whether the array is empty. The specific implementation is as follows:

if ($array === array()) {
  // $array 是空数组
} else {
  // $array 不是空数组
}

This method is very efficient because it does not require traversing the array. However, it requires an additional empty array to be defined in the code, which may lead to bloated code.

Summary

The above are four methods for judging whether an array is empty. Each of them has its own advantages and disadvantages. Choose the most suitable method for judgment based on the actual situation. If you need to quickly determine whether an array is empty, you can use the empty() or array() function; if you need to accurately determine whether an array is empty, you can use the count() or isset() function.

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