php determines whether array is empty

In PHP, it is very simple to determine whether an array is empty. There are several methods:

1. Use the empty function to determine whether an array is empty

The empty function can determine a variable Whether it is empty, including 0, "0", "", null, false, array(), etc., so it can also be judged whether an array is empty. The code is as follows:

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

2. Use the count function to determine

The count function can calculate the number of array elements. When the array is empty, the count function returns 0, so it can Use the count function to determine whether an array is empty. The code is as follows:

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

3. Use isset function to judge

isset function can determine whether a variable has been defined. When the array is empty, isset function returns false, so it can also Use the isset function to determine whether an array is empty. The code is as follows:

if (!isset($array)) { echo "数组为空"; } else { echo "数组不为空"; }

Note: The above three methods are suitable for data structures based on arrays, such as queues, stacks, etc.

For data structures that are not implemented based on arrays, such as linked lists, trees, etc., the above method is not applicable. At this time, other methods can be used to determine, for example: determining whether the pointer of the data structure is empty.

Summary:

To determine whether an array is empty, you can use functions such as empty, count, isset, etc. to determine whether an array is empty. However, for data structures that are not implemented based on arrays, specific judgment methods need to be used.

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