Use a for loop instead of foreach when direct index control is needed, such as skipping elements or manipulating the index manually. 2. For large numerically indexed arrays, for loops are more efficient because they avoid the overhead of PHP’s internal pointer and key-value unpacking. 3. When modifying array elements, for loops prevent lingering reference issues that can occur with foreach and &$value. 4. When processing multiple arrays in parallel, for loops provide clearer and more straightforward indexing than foreach alternatives. 5. Best practices include using for only with sequential indexed arrays, caching count($array), and avoiding modifications to array size during iteration—making for the better choice when index precision, performance, or parallel access is required.

When working with PHP arrays, foreach is often the go-to loop structure—clean, readable, and purpose-built for traversing arrays. But there are scenarios where a for loop not only matches foreach, but actually outperforms it in clarity, control, and efficiency. Understanding when and why to use a for loop over foreach can make your code faster and more intentional.

When You Need Index Control

The most compelling reason to use a for loop is when you need direct access to the array index—not just the value. While foreach can give you the key (with as $key => $value), it doesn't let you manipulate or jump around the index. A for loop, however, gives you full control.

$fruits = ['apple', 'banana', 'cherry', 'date', 'elderberry'];

// Skip every other element
for ($i = 0; $i < count($fruits); $i  = 2) {
    echo $fruits[$i] . "\n";
}

This outputs:
apple
cherry
elderberry

With foreach, you’d have to manually track the index and use modulo checks, which is less efficient and less clear.

Performance with Large Indexed Arrays

When dealing with large, numerically indexed arrays, for loops can be faster because they don’t rely on PHP’s internal pointer mechanism like foreach does. Also, count($array) can be cached to avoid repeated function calls:

$largeArray = range(1, 100000);
$length = count($largeArray); // Cache count

for ($i = 0; $i < $length; $i  ) {
    // Process $largeArray[$i]
    $sum  = $largeArray[$i];
}

In contrast, foreach creates a copy of the array when used on non-references (in older PHP versions), and even in modern PHP, the overhead of key-value unpacking adds up at scale.

Modifying Array Elements by Reference (Safely)

While foreach allows &$value to modify elements, it comes with caveats—especially if you reuse the loop variable later (it retains the last reference). A for loop avoids this trap entirely:

$numbers = [1, 2, 3, 4, 5];

for ($i = 0; $i < count($numbers); $i  ) {
    $numbers[$i] *= 2;
}

No risk of lingering references. Clean, predictable, and explicit.

Working with Multiple Arrays in Tandem

If you’re looping through two or more arrays of the same length in parallel (e.g., merging data), for is the natural choice:

$names = ['Alice', 'Bob', 'Charlie'];
$scores = [85, 92, 78];
$combined = [];

for ($i = 0; $i < count($names); $i  ) {
    $combined[] = [
        'name' => $names[$i],
        'score' => $scores[$i]
    ];
}

With foreach, you’d need array_keys or current/next tricks, making the code less readable.

Caveats and Best Practices

• Only use for on indexed, sequential arrays. It fails silently or breaks with associative or non-integer keys.
• Always cache count($array) if used in the condition to avoid performance hits.
• Avoid modifying the array size (adding/removing elements) during the loop—this can lead to skipped elements or infinite loops.

So while foreach remains the default for most array iteration, don’t overlook the for loop. When you need index manipulation, better performance on large datasets, or parallel array processing, for isn’t just an alternative—it’s the better tool. Know your data structure, and choose accordingly.

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