Loops

C-style for loop

The classic three-part for loop:

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for ($i = 0; $i < 5; $i++) {
    echo "$i ";
}
// Output: 0 1 2 3 4

All three parts are expressions — you can use any step value:

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// Count down
for ($i = 10; $i > 0; $i -= 3) {
    echo "$i ";
}
// Output: 10 7 4 1

// Step by 2
for ($i = 0; $i < 10; $i += 2) {
    echo "$i ";
}
// Output: 0 2 4 6 8

for-as loop (array iteration)

Iterate over arrays and objects with for...as:

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// Iterate values only
$colors = ["red", "green", "blue"];
for ($colors as $color) {
    echo "$color ";
}
// Output: red green blue

// Iterate key-value pairs
$person = [name: "Alice", age: 30, city: "NYC"];
for ($person as $key: $value) {
    echo "$key=$value ";
}
// Output: name=Alice age=30 city=NYC

Array destructuring in loops

Unpack nested arrays directly in the loop variable:

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$points = [[name: "a", price: 10], [name: "b", price: 20]];
for ($points as [$name, $price]) {
    echo "$name=$price ";
}
// Output: a=10 b=20

This is commonly used when iterating database results:

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$rows = [
    [id: 1, name: "Widget", price: 9.99],
    [id: 2, name: "Gadget", price: 19.99]
];
for ($rows as $row) {
    echo "$row.name: $row.price\n";
}

while loop

Execute code as long as a condition is true:

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$counter = 0;
while ($counter < 5) {
    echo "$counter ";
    $counter++;
}
// Output: 0 1 2 3 4

do-while loop

Execute the body at least once, then repeat while the condition is true:

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$i = 0;
do {
    echo "$i ";
    $i++;
} while ($i < 3);
// Output: 0 1 2

Useful for retry patterns and paginated API requests:

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$offset = 0;
do {
    $batch = $fetchBatch($offset);
    $processBatch($batch);
    $offset += count $batch;
} while (count $batch >= 100);

loop (infinite loop)

The loop keyword creates an infinite loop — use break to exit:

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$attempts = 0;
loop {
    $attempts++;
    $result = $tryConnect();
    if ($result) {
        break;
    }
    if ($attempts >= 3) {
        throw new @Exception("Connection failed after 3 attempts");
    }
}

break

Exit the current loop immediately:

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$items = ["apple", "banana", "cherry", "date"];
for ($items as $item) {
    if ($item == "cherry") {
        break;
    }
    echo "$item ";
}
// Output: apple banana

continue

Skip the rest of the current iteration and move to the next:

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$numbers = [1, 2, 3, 4, 5, 6];
for ($numbers as $n) {
    if ($n % 2 == 0) {
        continue; // Skip even numbers
    }
    echo "$n ";
}
// Output: 1 3 5

A practical example — skipping invalid records:

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for ($records as $record) {
    unless (exists $record.email) {
        continue;
    }
    unless ($record.email ~= "/^[^@]+@[^@]+$/") {
        continue;
    }
    $processRecord($record);
}