Which Array Transformation Method in PHP Offers the Best Performance?

Performance Comparison of Array Transformation Methods

To transform an array into another, we often use techniques like foreach, array_map with lambda/closure functions, or array_map with static functions. This article evaluates the performance differences between these approaches.

Foreach

Foreach is a classic method that iterates through an array, transforming each element individually. It creates a new array from the results:

$result = array();
foreach ($numbers as $number) {
    $result[] = $number * 10;
}
return $result;

Array_map with Lambda

Array_map with a lambda function combines the elements of an array using a provided callback. In this case, a lambda function multiplies each element by 10:

return array_map(function($number) {
    return $number * 10;
}, $numbers);

Array_map with Static Function

Array_map can also use a static function as its callback. Here, a static function named 'tenTimes' multiplies each element:

function tenTimes($number) {
    return $number * 10;
}
return array_map('tenTimes', $numbers);

Performance Analysis

Benchmarks using PHP 5.6, 7, and HHVM show that the array_map method, both with lambda and static functions, is consistently faster than foreach. This is because array_map uses the internal functions, which are optimized for speed.

However, when using closures with array_map and introducing external variables with 'use', the performance impact becomes significant. Foreach and array_map with named functions perform similarly in this scenario.

Conclusion

When efficiency is paramount, array_map should be used over foreach. If using closures with external variables, consider optimizing the code or using array_map with named functions instead. The choice ultimately depends on specific requirements and performance considerations.

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