How Can I Optimize Alternating Array Merging in PHP?

Alternately Merge Two Arrays in an Optimized Fashion

In the realm of programming, efficiently merging two arrays is a common task. While concatenation is straightforward, there may be instances where you require an alternating merge, interleaving values from both arrays. While a naive looping solution is available, it can be suboptimal from a performance standpoint.

For time-sensitive applications that necessitate frequent merging operations, a more efficient approach is desirable. PHP provides a built-in solution that achieves this optimization:

$count = count($a1);
for ($i = 0; $i < $count; $i++) {
    $newArray[] = $a1[$i];
    $newArray[] = $b1[$i];
}

This method pre-calculates the size of the resulting array and assigns values alternately from both input arrays, resulting in an optimized merge operation. Benchmarking demonstrates that this technique surpasses the naive looping approach, especially when executing thousands of merge operations:

// Pre-counting array size
$a1 = array(0, 1, 2);
$a2 = array(3, 4, 5);

$start = microtime(TRUE);
for ($t = 0; $t < 100000; $t++) {
    $newArray = array();
    $count = count($a1);
    for ($i = 0; $i < $count; $i++) {
        $newArray[] = $a1[$i];
        $newArray[] = $a2[$i];
    }
}
echo round(microtime(TRUE) - $start, 2); // 0.6

// Without pre-counting
$a1 = array(0, 1, 2);
$a2 = array(3, 4, 5);

$start = microtime(TRUE);
for ($t = 0; $t < 100000; $t++) {
    $newArray = array();
    for ($i = 0; $i < count($a1); $i++) {
        $newArray[] = $a1[$i];
        $newArray[] = $a2[$i];
    }
}
echo round(microtime(TRUE) - $start, 2); // 0.85

In conclusion, the built-in method with pre-counted array size offers a significant performance advantage for time-sensitive applications requiring frequent array merging operations.

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