宏观和preprocessor之间的区别 [英] Difference between macro and preprocessor

问题描述

据我了解，的#define嗒嗒8 是一个宏。同时，＃是pre处理器指令。

From what I understand , #define blah 8 is a macro . While , # is the pre-processor directive .

我们可以说＃包括，＃如果的#ifdef等。也是宏，或者是他们叫别的东西？抑或是宏观只是仅用于#define语句的一个术语？

Can we say #include,#if,#ifdef,etc. are also macros , or are they called something else ? Or is it that macro is just a term used for #define statements only?

的请如果我错了指正。的

推荐答案

与＃开始的行是的 preprocessing指令的。他们指示，告诉preprocessor做一些事情。

Lines that start with # are preprocessing directives. They are directives that tell the preprocessor to do something.

的#include ，＃如果， #IFDEF ，的#ifndef ，的#else ， #elif指令， #ENDIF ，的#define ，和#undef ，＃行， #ERROR 和的#pragma 都是preprocessing指令。 （A仅含行＃也是preprocessing指令，但没有任何效果。）

#include, #if, #ifdef, #ifndef, #else, #elif, #endif, #define, #undef, #line, #error, and #pragma are all preprocessing directives. (A line containing only # is also a preprocessing directive, but it has no effect.)

的#define嗒嗒8 为preprocessing指令，它不是一个宏。 等等是一个宏。这的#define preprocessing指令定义了一个名为宏等等由令牌取代了类对象宏 8 。

#define blah 8 is a preprocessing directive, it is not a macro. blah is a macro. This #define preprocessing directive defines the macro named blah as an object-like macro replaced by the token 8.

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