本文介绍了在C语言preprocessor例子的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
欲Çpreprocessor指令的一些实例中,如:
I want some examples of C preprocessor directives, such as:
#define pi 3.14
#define MAX 100
我只知道这个。
我想知道的比这更多,更多关于preprocessor指令。
I know only this.I want to know more than this, more about preprocessor directives.
推荐答案
最大的例子是
#include<stdio.h>
但也有相当数量。您还可以定义宏:
But there are a fair amount. You can also define macros:
#define MAX(X,Y) (((X) > (Y)) ? (X) : (Y))
和使用
#ifndef A_H
#define A_H
// code
#endif
有专有的扩展,编译器定义,让你给处理指令:
There are proprietary extensions that compilers define to let you give processing directives:
#ifdef WIN32 // WIN32 is defined by all Windows 32 compilers, but not by others.
#include <windows.h>
#else
#include <unistd.h>
#endif
和if语句原因也可用于注释
And the if statement cause also be used for commenting:
#if 0
int notrealcode = 0;
#endif
我经常使用的preprocessor进行调试版本:
I often use the preprocessor to make debug builds:
#ifdef EBUG
printf("Debug Info");
#endif
$ gcc -DEBUG file.c //debug build
$ gcc file.c //normal build
和其他人一样指出有很多地方可以得到更多的信息:
And as everyone else has pointed out there are a lot of places to get more information:
- http://predef.sourceforge.net/
- http://en.wikipedia.org/wiki/C%5Fpreprocessor
- http://gcc.gnu.org/onlinedocs/cpp/
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