宏和多行注释 [英] Macros and multi-line comments

问题描述

我需要在一组宏中包含多行注释，以便其中一个宏启动注释块，另一个宏结束注释块，如下所示：

I need to have multi-line comments within a group of macros so that one of the macros initiates a comment block and another concludes it, like this:

#define C_BEGIN /*
#define C_END */
... other macros

$

推荐答案

不能做以下推理。让我们假设是可能。

You can't do it for the following reasoning. Let's assume it is possible.

因此，您创建了一个用 / * 替换 / 。那么会发生什么呢？首先，从代码中删除注释。之后，预处理器将使用注释替换您的宏。之后，编译器会窒息：它不知道如何处理 / * 和 * / ，因为它根本不会面临这样的事情：在编译之前总是删除注释，所以它甚至不知道注释是什么。它可能会认为它是一个除法，其次是乘法。

So you created a macro that replaces itself with /*, and another for */. What happens then? First, the comments are removed from the code. After that, the preprocessor replaces your macros with the comments. After that, the compiler will choke: it doesn't know what to do with /* and */ because it simply never faces such things: the comments are always delete before the compilation, so it doesn't even know what a "comment" is. It will probably think it's a division followed by multiplication.

所以我们的假设是错误的，你不能这样做。

So our assumption is wrong and you can't do it.

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