Performance comparison between array_diff_ukey() and foreach loops

During PHP development, processing arrays is a very common task, and choosing the right function or method can not only improve code readability, but also significantly improve program performance. This article will use array_diff_ukey() and foreach loops as examples to compare their performance differences when processing arrays, and explore how to weigh and use them in actual development.

1. What is array_diff_ukey() ?

array_diff_ukey() is a function provided by PHP to compare the key names of two or more arrays, and compare them through a user-defined callback function, returning an array containing all keys in the first array but not in other arrays.

The syntax is as follows:

 array array_diff_ukey(array $array1, array $array2, callable $key_compare_func)

Example:

 function key_compare($a, $b) {
    return strcmp($a, $b);
}

$array1 = ["a" => "apple", "b" => "banana", "c" => "cherry"];
$array2 = ["b" => "blueberry", "d" => "date"];

$result = array_diff_ukey($array1, $array2, "key_compare");
print_r($result);

Output:

 Array
(
    [a] => apple
    [c] => cherry
)

2. Use foreach to achieve the same function

We can also use a foreach loop to implement a similar logic:

 $array1 = ["a" => "apple", "b" => "banana", "c" => "cherry"];
$array2 = ["b" => "blueberry", "d" => "date"];
$result = [];

foreach ($array1 as $key => $value) {
    if (!array_key_exists($key, $array2)) {
        $result[$key] = $value;
    }
}

print_r($result);

The output is the same:

 Array
(
    [a] => apple
    [c] => cherry
)

3. Performance comparison

Now let's take a look at the performance of both when dealing with large arrays.

 function key_compare($a, $b) {
    return strcmp($a, $b);
}

// Build large arrays
$array1 = [];
$array2 = [];

for ($i = 0; $i < 10000; $i++) {
    $array1["key$i"] = "value$i";
    if ($i % 2 == 0) {
        $array2["key$i"] = "value_other$i";
    }
}

// test array_diff_ukey()
$start = microtime(true);
$result1 = array_diff_ukey($array1, $array2, "key_compare");
$time1 = microtime(true) - $start;

// test foreach
$start = microtime(true);
$result2 = [];
foreach ($array1 as $key => $value) {
    if (!array_key_exists($key, $array2)) {
        $result2[$key] = $value;
    }
}
$time2 = microtime(true) - $start;

echo "array_diff_ukey(): {$time1} Second\n";
echo "foreach: {$time2} Second\n";

Results Analysis

• array_diff_ukey() may be slightly slow in performance because of the internal use of callback functions for key comparison, especially when the callback function itself is more complicated.

• Foreach is usually better performing, especially when logic is simple, because it avoids the overhead of function calls.

Of course, actual performance will vary depending on factors such as array size, server hardware, PHP version, etc. It is recommended to conduct actual measurements in performance-sensitive scenarios.

4. When to use which one?

V. Conclusion

Whether using array_diff_ukey() or a manual foreach loop, the most important thing is to make choices based on the specific business scenario. If you are developing a high-performance API or web service (such as https://m66.net/api/v1/data ), using foreach loops often gives you better control over logic and performance; in some business logic that focuses more on maintainability and expressivity, choosing built-in functions provided by PHP may be a better way.

I hope this article can help you better understand the advantages and disadvantages of both and make more reasonable decisions in future PHP projects.