＃线 [英] #line
问题描述
我不明白[文件]选项。
如果我写：
#line 100" file" ;
我将文件编号更改为从第100行开始，但是文件是什么。 ？
任何一个例子？
谢谢
Hi, I don''t understand [file] option.
if I write:
#line 100 "file"
I change file numeration to start to line 100 but what "file" ?
any example?
Thanks
推荐答案
6月6日，08：40，xdevel< xdevel1 ... @ gmail.comwrote：
On 6 Jun, 08:40, xdevel <xdevel1...@gmail.comwrote:
我不明白[文件选项。
如果我写：
#line 100" file"
我将文件编号更改为从第100行开始，但是文件是什么。 ？
任何一个例子？
Hi, I don''t understand [file] option.
if I write:
#line 100 "file"
I change file numeration to start to line 100 but what "file" ?
any example?
s 5s with google
" #line linenum filename
linenum与对于第一种形式，并具有相同的效果。
另外，filename是一个字符串常量。以下行和
报告的所有后续行都来自它指定的文件，
，直到其他地方发生变化为止。
它会影响宏__FILE__扩展到的内容。
-
Nick Keighley
恐龙来了又走了，我们Theriodonts仍然是
5s with google
"#line linenum filename
linenum is the same as for the first form, and has the same effect.
In addition, filename is a string constant. The following line and
all subsequent lines are reported to come from the file it specifies,
until something else happens to change that."
it affects what the macro __FILE__ expands to.
--
Nick Keighley
"The Dinosaurs have come and gone, we Theriodonts remain"
在文章< 11 ***************** *****@q69g2000hsb.googlegroups .com> ;,
xdevel< xd ******** @ gmail.comwrote：
In article <11**********************@q69g2000hsb.googlegroups .com>,
xdevel <xd********@gmail.comwrote:
>我不明白[文件]选项。
>Hi, I don''t understand [file] option.
>如果我写：
>if I write:
> #line 100文件
>#line 100 "file"
>我将文件编号更改为从第100行开始，但是文件是什么。 ？
>I change file numeration to start to line 100 but what "file" ?
>任何例子？
>any example?
无论你想要哪个文件;-)
C预处理器通常会放入#line
#include。例如，如果您的源xdev.c有
/ *这是对第1行的评论* /
#include< stdio.h>
/ *这是第3行* /
int foo：
然后预处理器可能将此扩展为
＃line 1" xdev.c"
＃line 1" stdio.h"
....实际stdio.h内容的行
#line 3" xdev.c"
int foo：
你可能会发生注意到我没有在预处理版本中重现评论
：评论会在预处理阶段转换为空格
。
＃line 1" xdev.c" part表示最初的下一行
来自xdev.c的第1行。之后的空行是什么
最初是xdev.c的第一行，但是因为
这是一个评论而被清空了。之后的行是包含stdio.h的地方，
所以stdio.h的扩展以标记#file 1" stdio.h"
开头说下一行最初来自stdio.h的第1行。
通常stdio.h的第一行是预处理器指令，所以
我显示一个空行，其中预处理器指令得到处理
并转换为空行（以保持行数一致）。
编译器保持相对于最后一行的计数，因此它会知道
表示...实际stdio.h内容的某些行发生了从bdio.h第2行开始的
。最终stdio.h完成并且
发出另一个#line，表示下一个源代码行
最初是xdev.c的第3行。再次，这是一个评论，
被淘汰。从最后一行#line开始再次计算，编译器
知道下一行必须最初来自
xdev.c的第4行。这就是编译器知道的，当它打印出该行的语法错误消息时，它应该抱怨
关于xdev.c的第4行。如果#line不存在，那么在预处理之后
已经扩展了stdio.h以及它所引入的所有内容，编译器
可能会认为它已经在线2500或者其他什么（stdio.h扩展了很多！）
并且用户抱怨
在5号线2503上出错是没有多大意义的行源文件！
-
当时我很年轻，但我也很朦胧。
- Christopher Priest
Whichever file you want ;-)
It is common for C preprocessors to put in #line as they expand each
#include . For example, if your source xdev.c had
/* this is a comment on line 1 */
#include <stdio.h>
/* this is line 3 */
int foo:
then the preprocessor might expand this to
#line 1 "xdev.c"
#line 1 "stdio.h"
.... some lines of actual stdio.h content
#line 3 "xdev.c"
int foo:
You might happen to notice that I didn''t reproduce the comments
in the preprocessed version: comments get converted to spaces
by the preprocessing phases.
The #line 1 "xdev.c" part indicates that the next line originally
came from line 1 of xdev.c . The empty line after that is what
was originally the first line of xdev.c but which got emptied because
it was a comment. The line after that is where stdio.h got included,
so the expansion of stdio.h begins with a marker #file 1 "stdio.h"
saying that the next line originally came from line 1 of stdio.h .
Usually the first line of stdio.h is a preprocessor directive, so
I show an empty line where the preprocessor directive got processed
and converted to an empty line (to keep the line counts consistant).
The compiler keeps count relative to the last #line, so it would know
that the "... some lines of actual stdio.h content" occured
starting at line 2 of stdio.h . Eventually stdio.h finishes and
another #line is emitted to indicate that the next source line
was originally line 3 of xdev.c . Again that was a comment that got
blanked out. Keeping count again from the last #line, the compiler
knows that the next line must have originally been from line 4 of
xdev.c . And that''s how the compiler knows, when it prints out
the syntax error message for that line, that it should be complaining
about line 4 of xdev.c . If #line did not exist, then after preprocessing
had expanded stdio.h and everything that it pulls in, the compiler
might think that it''s on line 2500 or whatever (stdio.h expands a lot!)
and it wouldn''t make much sense to the user to complain about
an error on line 2503 of a 5 line source file!
--
I was very young in those days, but I was also rather dim.
-- Christopher Priest
xdevel写道：
xdevel wrote:
>
我不是了解[file]选项。如果我写：
#line 100" file"
我将文件编号更改为从第100行开始，但是文件是什么？ ？
任何一个例子？
>
Hi, I don''t understand [file] option. if I write:
#line 100 "file"
I change file numeration to start to line 100 but what "file" ?
any example?
这与C语言无关，也完全不清楚b $ b。寻找一个处理你的系统的小组，并改善你的问题。
-
< http：/ /www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt>
< http://www.securityfocus.com/columnists/423>
< http://www.aaxnet.com/editor/edit043.html>
< http://kadaitcha.cx/vista/dogsbreakfast/index.html>
cbfalconer at maineline dot net
-
通过免费的Usenet帐户发布 http://www.teranews.com
This has nothing to do with the C language, and is also totally
unclear. Look for a group that deals with your system, and improve
your question.
--
<http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfocus.com/columnists/423>
<http://www.aaxnet.com/editor/edit043.html>
<http://kadaitcha.cx/vista/dogsbreakfast/index.html>
cbfalconer at maineline dot net
--
Posted via a free Usenet account from http://www.teranews.com
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