PHP array key-value exchange: Analysis of the advantages and disadvantages of common algorithms

Three common algorithms for exchanging array key values ​​in PHP have their own advantages and disadvantages: array_flip(): simple and efficient, but the values ​​must be unique and cannot handle multi-dimensional arrays. Manual traversal: can handle multi-dimensional arrays and control exceptions, but the code is longer and less efficient. ksort() array_keys(): can handle any type of array and control the sort order, but it is less efficient. Practical cases show that array_flip() is the most efficient, but when dealing with multi-dimensional arrays, manual traversal is more appropriate.

PHP array key-value exchange: Analysis of the advantages and disadvantages of common algorithms

In PHP, sometimes we need to exchange the positions of keys and values ​​in the array . This article will explore three common algorithms, analyze their advantages and disadvantages, and compare them through practical cases.

1. Built-in array_flip() Function

array_flip() is a built-in PHP function specifically used to interchange keys and values. Its syntax is very simple:

$swappedArray = array_flip($array);

Advantages:

• Easy to use, one line of code can complete the interchange
• High efficiency

Disadvantages:

• Values ​​must be unique, otherwise the keys will be overwritten
• Cannot handle multi-dimensional arrays

2. Manual traversal

We can use manual traversal to achieve key-value exchange:

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

Advantages:

• Can handle multi-dimensional arrays
• Can control exceptions

Disadvantages:

• Long code and low execution efficiency

3. Using ksort() and array_keys()

We can do this by using ksort() and array_keys() Function to indirectly implement key-value exchange:

$sortedArray = ksort($array);
$swappedArray = array_keys($sortedArray);

Advantages:

• Can handle any type of array
• Can control the sorting order

Disadvantages:

• Low execution efficiency

Practical case

The following is a practical case comparing the performance of these three algorithms:

$data = [
    'apple' => 'red',
    'banana' => 'yellow',
    'orange' => 'orange',
];

$start = microtime(true);
$swappedArray1 = array_flip($data);
$end = microtime(true);
echo "array_flip(): " . ($end - $start) . " seconds\n";

$start = microtime(true);
$swappedArray2 = [];
foreach ($data as $key => $value) {
    $swappedArray2[$value] = $key;
}
$end = microtime(true);
echo "Manual traversal: " . ($end - $start) . " seconds\n";

$start = microtime(true);
ksort($data);
$swappedArray3 = array_keys($data);
$end = microtime(true);
echo "ksort() + array_keys(): " . ($end - $start) . " seconds\n";

Output:

array_flip(): 0.000004006500244 seconds
Manual traversal: 0.000020980834961 seconds
ksort() + array_keys(): 0.000005984306335 seconds

We can see from the results, array_flip() Functions win on efficiency. For handling multidimensional arrays or unusual situations, manual traversal is more appropriate. ksort() array_keys() The efficiency of the method is also quite high, but it cannot control the sort order.

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