多行 DEFINE 指令？
我不是专家，所以对我宽容一些。这两个代码段之间有什么区别吗？
#define BIT3 (0x1
<
<
3)
static int a;
另外
#define BIT3 (0x1 << 3) static int a;
，有没有办法将第一行写成一行？这种多线样式有什么意义呢？下面的代码好不好？
#define BIT3 (0x1 << 3)
static int a;
I am not an expert, so go easy on me. Are there any differences between these two code segments?
#define BIT3 (0x1
<
<
3)
static int a;
and
#define BIT3 (0x1 << 3) static int a;
Also, is there a way to write the first in one line? What is the point of this multi-line style? Is the following code good?
#define BIT3 (0x1 << 3)
static int a;
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评论（3）
如果您有一个非常复杂的宏，如果它全部在一行上，则很难阅读（尽管不建议使用非常复杂的宏），那么多行宏很有用。
通常，您可以使用续行符
\编写多行定义。所以例如但是你不能用你的第一个例子来做到这一点。你不能像这样分割代币；
<<左移运算符的编写必须始终没有任何分隔空格，否则它将被解释为两个小于运算符。所以也许：这现在相当于你的第二个例子。
[虽然我不确定这个宏会有什么用处！]
A multi-line macro is useful if you have a very complex macro which would be difficult to read if it were all on one line (although it's inadvisable to have very complex macros).
In general, you can write a multi-line define using the line-continuation character,
\. So e.g.But you cannot do that with your first example. You cannot split tokens like that; the
<<left-shift operator must always be written without any separating whitespace, otherwise it would be interpreted as two less-than operators. So maybe:which is now equivalent to your second example.
[Although I'm not sure how that macro would ever be useful!]
例如：
您可以使用
\字符分隔行。请注意，它不是特定于宏的。每当您想要换行长行时，都可以在代码中添加\字符。For example:
You can separate the lines with the
\character. Note that it is not macro specific. You can add the\character in your code whenever you would like to break a long line.第一个应该不起作用。行应该用反斜杠然后换行符分隔。就像这样：
The first one should not work. Lines should be separated with backslash THEN newline. Like so: