Swapping Array Keys and Values in PHP: array_flip vs Manual Method

In PHP, swapping an array's keys and values can be done efficiently using two different methods, which are compared in this tutorial.

Method 1: array_flip() Function

$arr = ['foo' => 'bar', 'baz' => 'qux'];
$reversedArr = array_flip($arr);

Method 2: Manual Swapping

$arr = ['foo' => 'bar', 'baz' => 'qux'];

$newArray = [];
foreach ($arr as $key => $value) {
    $newArray[$value] = $key;
}

Practical Example

We use PHP's microtime(true) function to measure the execution time of both methods on a large array of 100,000 elements.

$arr = range(1, 100000); // create an array with 100,000 elements

// array_flip() method
$startTime = microtime(true);
$reversedArr = array_flip($arr);
$endTime = microtime(true);
$timeTakenArrayFlip = $endTime - $startTime;

// manual swapping method
$startTime = microtime(true);
$newArray = [];
foreach ($arr as $key => $value) {
    $newArray[$value] = $key;
}
$endTime = microtime(true);
$timeTakenManual = $endTime - $startTime;

The benchmark results show which approach is faster for large datasets.

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