为什么在 switch 和第一个 case 语句之间打开和关闭 PHP 标签会出错？

Question

作品：

    <?php switch ($student[$use_grade]) {
        case "K": ?>
            <?php echo 'works'; ?>
        <?php break; ?>
    <?php } ?>

无效：

    <?php switch ($student[$use_grade]) { ?>
        <?php case "K": ?>
            <?php echo 'works'; ?>
        <?php break; ?>
    <?php } ?>

解析错误：语法错误，意外 T_INLINE_HTML，应为 T_CASE 或 T_DEFAULT 或“}”

Answer 1

来自 PHP 的评论文档：

in the case of the switch statement, can be understood as follows; in any place where you can have an echo statement (an if block, a switch's case, whatever), that's where you can have the raw HTML. In PHP this basically gets handled just like that -- like an echo statement.

In between a switch and a case, though, you can't echo anything. By placing the switch and the case in two separate blocks of PHP, with a raw HTML newline echo'ed in between them, PHP basically had to try to find where that statement would be. And it can't be there, hence the difficulty.

http://www.php.net/manual/en/control-structures.alternative-syntax.php

Answer 2

内联 html（?> 和 <?php 之间的所有内容）在语法上与运算符相同，并且 switch 和第一个 [=13] 之间不允许使用运算符=].

来自 PHP 文档：

Any output (including whitespace) between a switch statement and the first case will result in a syntax error.

为什么在 switch 和第一个 case 语句之间打开和关闭 PHP 标签会出错？

Why Error if open and close PHP tags between switch and first case statement?

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