PHP array key-value exchange: Which solution is the most efficient?

PHP The best solution for key-value swapping arrays is array_flip(), because it is the most efficient and does not require the creation of temporary variables. Other solutions are less efficient, depending on the array type and requirements.

PHP array key-value exchange: Which solution is the most efficient

In PHP, you need to exchange the key-value pairs of the array When swapping, there are several methods to choose from, each with different efficiencies. Below is an analysis of these methods, along with recommendations for best practices for different scenarios.

Option 1: array_flip()

<?php
$array = ['a' => 1, 'b' => 2, 'c' => 3];
$flippedArray = array_flip($array);

print_r($flippedArray);
// 输出：
// [1 => 'a', 2 => 'b', 3 => 'c']

Option 2: array_combine()

<?php
$keys = ['a', 'b', 'c'];
$values = [1, 2, 3];

$flippedArray = array_combine($values, $keys);

print_r($flippedArray);
// 输出：
// [1 => 'a', 2 => 'b', 3 => 'c']

Option 3: Function definition

<?php
function flipArray($array) {
  $flippedArray = [];

  foreach ($array as $key => $value) {
    $flippedArray[$value] = $key;
  }

  return $flippedArray;
}

$array = ['a' => 1, 'b' => 2, 'c' => 3];
$flippedArray = flipArray($array);

print_r($flippedArray);
// 输出：
// [1 => 'a', 2 => 'b', 3 => 'c']

Option 4: Deconstruction

<?php
$array = ['a' => 1, 'b' => 2, 'c' => 3];

[$flippedArray] = [array_flip($array)];

print_r($flippedArray);
// 输出：
// [1 => 'a', 2 => 'b', 3 => 'c']

Practical case

Suppose there is a program containing the student name and Array of grades:

<?php
$students = [
  'Alice' => 90,
  'Bob' => 85,
  'Carol' => 95
];

To sort student names by grade, you can use the following code:

<?php
// 键值互换数组
$flippedStudents = array_flip($students);

// 键（分数）排序
ksort($flippedStudents);

// 获取排序的键（学生姓名）
$sortedNames = array_keys($flippedStudents);

print_r($sortedNames);
// 输出：
// [Bob, Alice, Carol]

Efficiency Analysis

Option 1: array_flip() is the most efficient because it is a built-in function of PHP and does not require the creation of any temporary variables.

Option 2: array_combine() is less efficient than array_flip() because it requires two separate arrays to combine.

Option 3: The efficiency of the custom function is lower than array_flip() because it requires the use of a loop to traverse the array.

Option 4: Destructuring is as efficient as array_flip(), but it only works when a composite array needs to be flipped (i.e. contains an array as a value).

Therefore, for most use cases, array_flip() is the most efficient solution for key-value swapping arrays.

The above is the detailed content of PHP array key-value exchange: Which solution is the most efficient?. For more information, please follow other related articles on the PHP Chinese website!