New functions in PHP8: multiple uses of array_key_last()

With the release of PHP8, we have ushered in many new features and functions, one of the important new functions is array_key_last(). The function of this function is to return the last key name of an array. In this article, we will introduce the various uses of array_key_last().

First use: delete the last element

There are often scenarios where we need to delete the last element in an array. The traditional way is to use the end() and key() functions Get the last key name and then delete it using the unset() function. However, this method is cumbersome and not intuitive enough. Now, we can use the array_key_last() function to simplify the code:

$array = [1, 2, 3];
$key = array_key_last($array);
unset($array[$key]);

This way we can easily delete the last element of the array.

Second use: Get the second to last key name

Sometimes, we need to get the second to last key name in an array. This purpose can also be implemented using the array_key_last() function, combined with the array_slice() function:

$array = [1, 2, 3, 4];
$key = array_key_last($array);
$prevKey = array_key_last(array_slice($array, 0, $key, true));

Here, we first use the array_slice() function to obtain the subarray of the previous key name of the last key name. , and then use the array_key_last() function to obtain its corresponding key name. In this way, we can get the penultimate key name very conveniently.

Third use: Get the value of the last element

In addition to getting the last key name, we can also get the value of the last element through the array_key_last() function. This purpose is relatively simple. You only need to use the subscript of the array to access it after getting the last key name:

$array = [1, 2, 3];
$key = array_key_last($array);
$value = $array[$key];

In this way, we can easily get the value of the last element in the array.

Fourth use: Check whether the array is empty

When judging whether an array is empty, we usually use the count() function to count the number of array elements. If it is 0, It is judged as empty. However, the execution time of the count() function is relatively slow, which can cause performance problems especially when the array is very large. Now, we can use the array_key_last() function to determine whether an array is empty:

$array = [1, 2, 3];
if (!array_key_last($array)) {
  echo '数组为空';
}

In this way, we can quickly determine whether an array is empty.

Fifth use: Get the value of the second to last element

With the help of the array_key_last() function, we can also easily get the value of the second to last element in the array. This method is similar to the method of obtaining the penultimate key name:

$array = [1, 2, 3, 4];
$key = array_key_last($array);
$prevKey = array_key_last(array_slice($array, 0, $key, true));
$value = $array[$prevKey];

In this way, we can easily obtain the value of the penultimate element in the array.

In general, the array_key_last() function is very practical and can help us simplify the code and improve efficiency. Whether you are deleting the last element or getting the penultimate key or element, you can do it easily.

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