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电梯直达

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发表于 2009-07-03 23:16 |只看该作者 |倒序浏览

我的 a.c 的内容只有
＃include<limits.h>
（我只想看看这个 limits.h 头文件里是些什么东西。）
通过 [root@localhost H]# gcc -E a.c -o a.i 打开文件 a.i 后怎么出现些以＃符号开头的东东呢？这些以＃开头的东东什么意思？好像C语言里没有这种语法阿？

[root@localhost H]# cat a.i
# 1 "c.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "c.c"
# 1 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 1 3 4
# 11 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 3 4
# 1 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/syslimits.h" 1 3 4

# 1 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 1 3 4
# 122 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 3 4
# 1 "/usr/include/limits.h" 1 3 4
# 27 "/usr/include/limits.h" 3 4
# 1 "/usr/include/features.h" 1 3 4
# 329 "/usr/include/features.h" 3 4
# 1 "/usr/include/sys/cdefs.h" 1 3 4
# 313 "/usr/include/sys/cdefs.h" 3 4
# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 314 "/usr/include/sys/cdefs.h" 2 3 4
# 330 "/usr/include/features.h" 2 3 4
# 352 "/usr/include/features.h" 3 4
# 1 "/usr/include/gnu/stubs.h" 1 3 4

# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 5 "/usr/include/gnu/stubs.h" 2 3 4

# 1 "/usr/include/gnu/stubs-64.h" 1 3 4
# 10 "/usr/include/gnu/stubs.h" 2 3 4
# 353 "/usr/include/features.h" 2 3 4
# 28 "/usr/include/limits.h" 2 3 4
# 145 "/usr/include/limits.h" 3 4
# 1 "/usr/include/bits/posix1_lim.h" 1 3 4
# 153 "/usr/include/bits/posix1_lim.h" 3 4
# 1 "/usr/include/bits/local_lim.h" 1 3 4
# 36 "/usr/include/bits/local_lim.h" 3 4
# 1 "/usr/include/linux/limits.h" 1 3 4
# 37 "/usr/include/bits/local_lim.h" 2 3 4
# 154 "/usr/include/bits/posix1_lim.h" 2 3 4
# 146 "/usr/include/limits.h" 2 3 4

# 1 "/usr/include/bits/posix2_lim.h" 1 3 4
# 150 "/usr/include/limits.h" 2 3 4
# 123 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 2 3 4
# 8 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/syslimits.h" 2 3 4
# 12 "/usr/lib/gcc/x86_64-redhat-linux/4.1.2/include/limits.h" 2 3 4
# 2 "c.c" 2
[root@localhost H]#

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www_xylove

版主

论坛徽章:: 7

2楼 [报告]

发表于 2009-07-04 01:05 |只看该作者

批注吧

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gamester88

丰衣足食

论坛徽章:: 5

3楼 [报告]

发表于 2009-07-04 08:06 |只看该作者

C语言中
#开头的是预处理指令，不是C语句的一部分
#开头的语句，在预处理阶段，由预处理器处理，例如：
#include <stdio.h>
预处理器会将stdio.h文件的内容加入到当前文件的头部，而
#define CONST 10
则会将文件中的CONST，用10代替（是直接代替）
预处理完毕后，才对文件进行编译。