Array iteration in PHP8.0

With the release of PHP8.0, the array iteration method has also received some new improvements and enhancements. These improvements not only make it easier for developers to handle array data, but also improve code readability and performance.

In this article, we will discuss the new array iteration methods in PHP8.0, including the following:

1. Return value type declaration of array_map()

In PHP8.0, the array_map() method adds a return value type declaration. Developers can add ": array" in front of the method signature to specify the return value type as an array.

For example:

function map(array $data): array {

return array_map(static fn($x) => $x + 1, $data);

}

In the above example, the map() method receives an array as a parameter and returns a new array after incrementing each element by 1.

2. Parameter passing improvements of the array_filter() method

In PHP8.0, the parameters of the array_filter() method can be passed by reference, so that they can be modified inside the callback function Array data.

For example:

$data = [1, 2, 3, 4, 5];
$even = [];
function is_even($x) {

global $even;
if ($x % 2 === 0) {
    $even[] = $x;
    return true;
}
return false;

}
array_filter($data, 'is_even');
var_dump($even); // [2, 4]

In the above example, we defined a The is_even() function returns true if the passed parameter is an even number, otherwise it returns false. Inside the is_even() function, we also modify the value of the $even array, which is used to store all even elements.

3. Type declaration of array_reduce() method

The array_reduce() method in PHP8.0 also has a new return value type declaration, which developers can add in front of the method signature Add ": mixed" to specify the type of return value.

For example:

function sum(array $data): int {

return array_reduce($data, static fn($acc, $x) => $acc + $x, 0);

}

In the above example, the sum() method receives an array as argument and returns the sum of all elements.

4. array_key_first() and array_key_last() methods

In PHP8.0, we can use the array_key_first() and array_key_last() methods to get the first of the array and the last key name. These two methods are particularly suitable for code that needs to operate on arrays based on keys.

For example:

$data = ['foo' => 1, 'bar' => 2, 'baz' => 3];
$first_key = array_key_first ($data); // 'foo'
$last_key = array_key_last($data); // 'baz'

In the above example, we used the array_key_first() and array_key_last() methods to Get the first and last key name of the array $data.

In addition to the above-mentioned new methods, PHP8.0 also performs performance optimization and error handling improvements on some methods, such as in_array() and array_search() methods.

In short, in PHP8.0, the array iteration experience is more convenient and flexible, as well as more powerful and efficient. Developers can choose appropriate methods to process array data based on actual needs, making the code more standardized and easier to maintain.

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