New functions in PHP8: new method for array_is_list()

PHP8 is the latest PHP version, focusing on improving developer efficiency and optimizing code performance. Among them, the new function array_is_list() is a very practical tool in PHP8. Its function is to determine whether an array is an index array and whether the key values ​​are sequentially increasing integers. In this article, the new method of array_is_list() function will be discussed in detail.

First, let’s take a look at the basic usage of the array_is_list() function. This function accepts an array as parameter and returns a boolean value. Returns true if the array is an indexed array and the keys are in increasing order, false otherwise. The following is an example:

$array = [0 => 'foo', 1 => 'bar', 2 => 'baz'];
var_dump(array_is_list($array)); // true

$array = [0 => 'foo', 2 => 'baz', 1 => 'bar'];
var_dump(array_is_list($array)); // false

Before PHP8, if we wanted to determine whether an array was an indexed array and whether the order of the key names was increasing, we needed to use a lot of code, but now there is the array_is_list() function , greatly simplifying the amount of code.

So, in PHP8, what new methods are added to the array_is_list() function? Let’s look at it one by one:

1. Determine whether there are duplicate indexes

In our judgment process, if there are duplicate indexes in the array, it cannot be regarded as an index. Array, in this case the array_is_list() function will return false. This new method is implemented using array_is_list($array, true), for example:

$array = [0 => 'foo', 1 => 'bar', 2 => 'baz', 2 => 'qux'];
var_dump(array_is_list($array, true)); // false

2. Supports string key names

Although index arrays are integers in most cases Key name, but in some cases it is also possible to use strings as key names for indexing. Before PHP8, using the array_values() or sort() function would cause the values ​​of these string key names to disappear. In the new version of the array_is_list() function, it is supported to retain the string key name while judging the index array. For example:

$array = ['foo' => 'bar', 'baz' => 'qux', 'corge'];
var_dump(array_is_list($array, false, true)); // false

In the above example, $array is not an index array, but because we have set the third parameter to true and then the second parameter to false, it returns false , and retains the value of the string key name.

3. Supports selecting an array range for judgment

Before PHP8, we had to judge whether an array was an index array and whether the key value was incrementing. We needed to traverse the entire array. to get results. However, in the new version of the array_is_list() function, you can specify a range and only judge the key names within the range. For example:

$array = [0 => 'foo', 1 => 'bar', 2 => 'baz', 3 => 'qux'];
var_dump(array_is_list($array, false, false, 0, 2)); // true

In the above example, we specify the range as keys with key names from 0 to 2, i.e. [0=>'foo',1=>'bar',2=> ;'baz'], and we still set the second parameter to false (that is, the key names are not increasing sequentially), but because the key names in the range all comply with the increasing rules, the return result is true.

Through the above analysis, we can see that the array_is_list() function has received multiple upgrades in PHP8, which can provide convenience when judging various array types at the same level. Whether developing applications or maintaining existing code, it can greatly improve development efficiency and optimize code performance, providing more practical support for the promotion and application of PHP8.

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