Array function in PHP8: array_key_first(), tips for getting the first key name of an array

The new array function array_key_first() in PHP8 is used to obtain the first key name of a given array. In many cases, you need to get the first element in an array, then you can use this function. This article will introduce how to use the array_key_first() function and the convenience it brings.

1. Use of array_key_first() function

The use of array_key_first() function is very simple. You only need to pass in an array to get the first key name of the array. An example is as follows:

$array = ['first' => 1, 'second' => 2, 'third' => 3];
$first_key = array_key_first($array);
echo $first_key; // 输出：first

In this example, an associative array is used, and the first key name of the array, which is 'first', is obtained through the array_key_first() function.

2. Advantages of array_key_first()

Before PHP8, there was no built-in function that could easily obtain the first key name of the array. Although you can use the reset() function to get the first element of the array, this function only returns the value of the element and cannot return the key name. Therefore, in PHP7 and below, you need to write some code yourself to get the first key name of the array. For example, use the array_keys() function to get all the key names of the array, and then get the first key name.

But in PHP8, the emergence of the array_key_first() function makes it very simple and convenient to obtain the first key name of the array. At the same time, using the array_key_first() function also has the following advantages:

1. Higher efficiency

Using the array_key_first() function can avoid using the reset() function or manual acquisition A list of key names for the array, thus improving the efficiency of the code.

2. More concise code

Using the array_key_first() function can make the code more concise and easier to maintain. This is especially important for long-term maintained code bases.

3. The combined use of array_key_first() and other functions

The array_key_first() function can be used in combination with other functions to further improve the efficiency and readability of the code. Two common ways of combined use are introduced below.

1. Use array_key_first() and list() to get the first element of the array

You can use array_key_first() and list() to get the first element of the array elements and corresponding key names. An example is as follows:

$array = ['first' => 1, 'second' => 2, 'third' => 3];
$first_key = array_key_first($array);
list($first_value,) = $array[$first_key];
echo "键名：{$first_key}，键值：{$first_value}"; // 输出：键名：first，键值：1

In this example, the list() function is used to deconstruct the array, thereby obtaining the first element of the array and the corresponding key name.

2. Use array_key_first() and array_slice() to get all elements except the first element of the array.

You can use array_key_first() and array_slice() functions to get all elements. to get all elements except the first element of the array. An example is as follows:

$array = ['first' => 1, 'second' => 2, 'third' => 3];
$first_key = array_key_first($array);
$slice = array_slice($array, 1, count($array) - 1, true);
print_r($slice); // 输出：Array ( [second] => 2 [third] => 3 )

In this example, the array_slice() function is used to obtain all elements except the first element of the array, and the key name is retained through the true parameter.

4. Summary

array_key_first() is one of the new functions in PHP8, used to obtain the first key name of the array. Its appearance makes the code more concise and efficient, and can be used in conjunction with other functions to improve the readability of the code. During the development process, if you need to get the first element of the array, you might as well try the array_key_first() function. I believe it will bring you a lot of convenience.

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