Functions in PHP8: efficient operation methods for array_key_first(), array_key_last() and array_column()

PHP8 is the latest version of the PHP language, which introduces some very useful new features and functions. This article will introduce three new functions in PHP8: array_key_first(), array_key_last() and array_column(), and discuss their efficient operation methods.

1. array_key_first()

array_key_first() function returns the first key name in the array. This function is very useful because in previous versions, when you wanted to get the key value of the first element, you had to use the reset() function. However, the reset() function resets the array pointer and returns not only the key name of the element, but also its value. This can cause problems in some situations.

Using the array_key_first() function can avoid these problems, and it is also more intuitive and easy to understand. The following is an example of using the array_key_first() function:

$array = ['foo' => 1, 'bar' => 2, 'baz' => 3];
$firstKey = array_key_first($array);
echo $firstKey; // 输出 'foo'

2. array_key_last()

array_key_last() function returns the last key name in the array, which is the same as array_key_first() Similar to the function, this function is also very useful. In previous versions, when you wanted to get the key name of the last element, you had to use the end() function. However, the end() function moves the array pointer to the last element and returns the value of that element, which can also cause problems.

Using the array_key_last() function can avoid these problems, and it is also more intuitive and easy to understand. Here is an example of using the array_key_last() function:

$array = ['foo' => 1, 'bar' => 2, 'baz' => 3];
$lastKey = array_key_last($array);
echo $lastKey; // 输出 'baz'

3. array_column()

array_column() function returns a specified column in the array. This function is very useful, especially when working with large amounts of data. In previous versions, when you wanted to get a column of data from a multidimensional array, you had to use a loop or the array_map() function.

Using the array_column() function can greatly simplify the code and improve execution efficiency. Here is an example of using the array_column() function:

$data = [
    ['id' => 1, 'name' => 'Alice', 'age' => 20],
    ['id' => 2, 'name' => 'Bob', 'age' => 23],
    ['id' => 3, 'name' => 'Charlie', 'age' => 25],
];

$names = array_column($data, 'name');
print_r($names); // 输出 ['Alice', 'Bob', 'Charlie']

If you want to get multiple columns, you can use an array as the second parameter. The following is an example of using an array as the second parameter:

$data = [
    ['id' => 1, 'name' => 'Alice', 'age' => 20],
    ['id' => 2, 'name' => 'Bob', 'age' => 23],
    ['id' => 3, 'name' => 'Charlie', 'age' => 25],
];

$result = array_column($data, ['id', 'name']);
print_r($result);
// 输出 [
//     ['id' => 1, 'name' => 'Alice'],
//     ['id' => 2, 'name' => 'Bob'],
//     ['id' => 3, 'name' => 'Charlie']
// ]

4. Efficient operation method

The above three functions are very useful in PHP8, but if not Use with care, they can also cause performance issues. Here are some efficient methods of operation:

• Use the array_key_first() and array_key_last() functions outside the loop whenever possible. Calling these functions repeatedly in a loop wastes performance.
• If you only need one column of data, you can use a foreach loop instead of the array_column() function. In a loop, use the [] operator to get the specified column.
• When using the array_column() function, only get the required columns. If you get the entire array, you waste memory and processing time.

To sum up, the array_key_first(), array_key_last() and array_column() functions in PHP8 are very useful. Using them can make the code more intuitive, easier to understand, and improve execution efficiency. However, care must be taken to operate efficiently when using these functions to avoid performance issues.

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