PHP Loops

PHP Loops: Repeating Tasks with foreach, for, and while

PHP loops run a block of code repeatedly until a condition turns false or every item in a collection is processed. Choosing the right loop keeps your code concise and prevents infinite-loop crashes.

Choosing the Right PHP Loop

Each loop fits a distinct iteration pattern in backend code.

<?php
declare(strict_types=1);

$cartItems = [
    ["name" => "USB-C Hub", "price" => 35.00],
    ["name" => "HDMI Cable", "price" => 12.50],
    ["name" => "Laptop Stand", "price" => 44.00],
];

$total = 0.0;
foreach ($cartItems as $index => $item) {
    $total += $item['price'];
    echo ($index + 1) . ". {$item['name']} - $" . number_format($item['price'], 2) . PHP_EOL;
}

echo "Cart Total: $" . number_format($total, 2) . PHP_EOL;

Controlling Loops with break, continue, and for

Use continue to skip the rest of the current iteration and break to exit the loop early once you find what you need.

<?php
declare(strict_types=1);

for ($attempt = 1; $attempt <= 5; $attempt++) {
    if ($attempt === 2) {
        continue; // Skip retry #2
    }
    echo "Checking service health (attempt {$attempt})" . PHP_EOL;
    if ($attempt === 4) {
        echo "Service healthy! Stopping retries." . PHP_EOL;
        break;
    }
}

Common Mistakes to Avoid

• Infinite while loops: Always update the condition variable inside the loop body, or ensure a break condition is reachable.
• Calling count($items) inside every for condition: Store $count = count($items); before the loop, or simply use foreach.
• Leaving a reference active after foreach ($arr as &$val): Always call unset($val); right after a by-reference foreach so later variables do not overwrite the last array element.

Frequently Asked Questions

Which loop is fastest for arrays in PHP?

foreach is the cleanest and fastest way to traverse PHP arrays, because PHP arrays are ordered hash maps internally rather than plain C arrays.

When should I use do...while instead of while?

Use do...while when the loop body must run at least once before checking whether to repeat, such as polling a queue or generating a unique slug.

How do I break out of nested loops at once?

Pass a numeric level to break or continue, such as break 2; to exit both the inner and outer loop together.