do-while 循环的范围? [英] Scope of do-while loop?

问题描述

在 Java 中，do-while 循环的主体和循环条件不属于同一范围.所以下面的代码不会编译:

In Java, the body of a do-while loop and the loop condition do not belong to the same scope. So the following code won't compile:

do {
    boolean b = false;
} while (b); // b cannot be resolved to a variable

但这段代码对我来说确实有意义.

But this code does make sense to me.

另外，如果body和condition在同一个范围内，我也找不到任何陷阱；由于主体总是会被执行，而 Java 没有 Goto，我不知道如何跳过最外层 do-while 主体范围中的变量声明.即使有可能，编译器也总能检测到这种可能性，然后产生编译时错误.

Also, I cannot find any pitfalls if the body and the condition are in the same scope; since the body will always get executed, and Java does not have Goto, I don't know how a variable declaration in the outermost do-while body scope could be skipped. Even if it is possible, the compiler could always detect such possibility and then produce compile time errors.

这种行为是否有任何原因(除了将 do-while 循环保持为与 while 相同的格式)?我真的很好奇.感谢您的任何投入！

Is there any reason for this behavior (aside from keeping the do-while loop in the same format as while)? I am really curious. Thanks for any inputs!

推荐答案

因为这是 Java 中定义作用域的一种方式；{} 里面是一个新的作用域.

Because that's one way scope is defined in Java; inside {} is a new scope.

IMO 对单个构造进行特殊处理没有多大意义.

IMO it wouldn't make much sense to special-case a single construct.

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