C代码宏/＃定义缩进？
我很好奇，为什么我看到此格式，几乎所有C宏：
I'm curious as to why I see nearly all C macros formatted like this:
#ifndef FOO
# define FOO
#endif
或者这样：
#ifndef FOO
#define FOO
#endif
但从来没有这样的：
But never this:
#ifndef FOO
#define FOO
#endif
（而且，Vim的 = 运营商似乎只算前两个是正确的。）
(moreover, vim's = operator only seems to count the first two as correct.)
这是由于可移植性语言编译器之间的问题，还是仅仅是一个标准的做法？
Is this due to portability issues among compilers, or is it just a standard practice?
IIRC，老年çpreprocessors要求＃要上线的第一个字符（虽然我从来没有实际遇到一个有这个要求） 。
IIRC, older C preprocessors required the # to be the first character on the line (though I've never actually encountered one that had this requirement).
我从来没有见过你的code喜欢你的第一个例子。我平时写preprocessor指令作为你的第二个例子。我发现，它在视觉上与实际code的压痕较少受干扰（不，我用C写了）。
I never seen your code like your first example. I usually wrote preprocessor directives as in your second example. I found that it visually interfered with the indentation of the actual code less (not that I write in C anymore).
的 GNU C preprocessor手动说：
preprocessing指令是在线路
你的程序以'＃'开始。
在空白前后允许
在'＃'。
Preprocessing directives are lines in your program that start with '#'. Whitespace is allowed before and after the '#'.