php - "break 2"是什么意思？

Question

我总是使用和看到只有“break”的例子。这是什么意思:

 <?php 
    while ($flavor = "chocolate") { 
      switch ($flavor) { 
        case "strawberry"; 
            echo "Strawberry is stock!"; 
            break 2;    // Exits the switch and the while 
        case "vanilla"; 
            echo "Vanilla is in stock!"; 
            break 2;   // Exits the switch and the while 
        case "chocolate"; 
            echo "Chocolate is in stock!"; 
            break 2;    // Exits the switch and the while 
        default;     
            echo "Sorry $flavor is not in stock"; 
            break 2;    // Exits the switch and the while 
      } 
    } 
    ?>

'break' 语句是否有更多可用选项？

Answer 1

来自PHP docs on break :

break accepts an optional numeric argument which tells it how many nested enclosing structures are to be broken out of.

正如评论中所指出的，它打破了 switch 和 while。

以下示例将跳出所有 foreach 循环:

foreach (...) {
  foreach (..) {
    foreach (...) {
      if ($condition) {
        break 3;
      }
    }
  }
}