是否在扩展宏之前处理预处理器指令？
Are preprocessor directives processed before macros are expanded?
是否在扩展宏之前处理预处理器指令？
谢谢
是也不是。每个预处理器指令都定义了自己与宏替换的交互。一般规则是 (C++11 16/6):
The preprocessing tokens within a preprocessing directive are not subject to macro expansion unless otherwise
stated.
另一个相关的一般规则是 16/1：
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the following constraints:
The first token in the sequence is a # preprocessing token that (at the start of translation phase 4) is either
the first character in the source file (optionally after white space containing no new-line characters) or that
follows white space containing at least one new-line character. The last token in the sequence is the first newline
character that follows the first token in the sequence. A new-line character ends the preprocessing
directive even if it occurs within what would otherwise be an invocation of a function-like macro.
（翻译阶段 4 是预处理）。
个别指令的一些规则：
#if 和 #elif 在其参数中扩展宏，defined (16.1/4).
[=39 的参数除外=]
#include 在其参数中扩展宏；它们最终必须扩展为由 "" 或 <>.
#line 在其参数中扩展宏；它们最终必须扩展为 #line (16.4/5)
是否在扩展宏之前处理预处理器指令？
谢谢
是也不是。每个预处理器指令都定义了自己与宏替换的交互。一般规则是 (C++11 16/6):
The preprocessing tokens within a preprocessing directive are not subject to macro expansion unless otherwise stated.
另一个相关的一般规则是 16/1：
A preprocessing directive consists of a sequence of preprocessing tokens that satisfies the following constraints: The first token in the sequence is a
#preprocessing token that (at the start of translation phase 4) is either the first character in the source file (optionally after white space containing no new-line characters) or that follows white space containing at least one new-line character. The last token in the sequence is the first newline character that follows the first token in the sequence. A new-line character ends the preprocessing directive even if it occurs within what would otherwise be an invocation of a function-like macro.
（翻译阶段 4 是预处理）。
个别指令的一些规则：
[=39 的参数除外=]#if和#elif在其参数中扩展宏，defined(16.1/4).#include在其参数中扩展宏；它们最终必须扩展为由""或<>. 分隔的字符串
#line在其参数中扩展宏；它们最终必须扩展为#line(16.4/5) 的非宏参数的有效语法