PHP有哪些控制流构造？

<?php
if ($score >= 90) {
    $grade = "A";
} elseif ($score >= 80) {
    $grade = "B";
} else {
    $grade = "F";
}

// ternary and null coalescing
$status = $age >= 18 ? "adult" : "minor";
$name = $input ?? "default";        // ?? — use default if null/unset (PHP 7+)
$value ??= "x";                      // ??= assign if null (PHP 7.4)

switch ($day) {
    case "Sat":
    case "Sun":
        $type = "weekend"; break;   // ⚠️ break needed or it falls through
    default:
        $type = "weekday";
}

// match (PHP 8) — cleaner: returns a value, STRICT comparison, NO fall-through
$type = match($day) {
    "Sat", "Sun" => "weekend",     // multiple values, no break needed
    default => "weekday",
};

for ($i = 0; $i < 10; $i++) { }

foreach ($items as $item) { }                    // iterate array values
foreach ($map as $key => $value) { }             // keys + values — the PHP idiom for arrays

while ($condition) { }
do { } while ($condition);

foreach ($items as $item) {
    if ($item->skip) continue;    // skip to next iteration
    if ($item->stop) break;        // exit the loop
}