David Warner写道：

David Warner wrote:

问候！

我需要写一些C代码将在从stdin读取或从argv获取文件名之间决定并处理它。

程序需要像所有典型的unix实用程序一样工作
要处理的文件是从管道/流或argv提供的。

lp，tr，grep等实用工具。

所以，当命令：

cat filename | grep -i> filename2



grep -i filename> filename2

执行，这就像我需要的programmtic接口。

我已经尝试了从getc，getchar，read，gets，
等我能想到的一切一切都行不通。我在返回值上测试EOF或NULL
并且程序只是在终端读取时挂起。所以，命令：

cat filename | testprogram -dvalue

挂在stdin的阅读上，我从来没有测试过EOF。

我缺少什么？

Greetings!

I need to write some C code that will decide between either reading from
stdin or take a file name from argv and process it.

The program needs to work like all of the typical unix utilities where
the file to process is either provided from a pipe/stream or argv.

Utilities like lp, tr, grep, etc.

So, when the command:

cat filename | grep -i > filename2

or

grep -i filename > filename2

executes, this acts like the programmtic interface i need.

I have tried everything I can think of from getc, getchar, read, gets,
etc. which all did not work. I test for EOF or NULL on the return values
and the program just hangs on a terminal read. So, the command:

cat filename | testprogram -dvalue

hangs on the reading from stdin and I never get to test for EOF.

What am i missing?

>
可能你可以显示你的代码，看看有什么遗漏。这个工作。

Probably you can show your code to see what''s missing. This one works.

cat simplecat.c

#include< stdio.h>

#include< stdlib.h>


#define BUF_SIZE 100

int main（int argc，char ** argv）

{char buf [BUF_SIZE + 1];

FILE * inp;


if（argc == 2）

{inp = fopen（argv [1]，" r"）;

if（！inp）

{return EXIT_FAILURE;

}

}

其他

{inp = stdin;

}

while（fgets（buf，sizeof buf，inp））

{printf（"％s"，buf）;

}

fclose（inp）;

返回EXIT_SUCCESS;

}

ishs

cat simplecat.c
#include <stdio.h>
#include <stdlib.h>

#define BUF_SIZE 100

int main(int argc, char ** argv)
{ char buf[BUF_SIZE + 1];
FILE * inp;

if(argc == 2)
{ inp = fopen(argv[1], "r");
if(!inp)
{ return EXIT_FAILURE;
}
}
else
{ inp = stdin;
}
while(fgets(buf, sizeof buf, inp))
{ printf("%s", buf);
}
fclose(inp);
return EXIT_SUCCESS;
}
ishs

>

在文章< da **************************** @ corp.supernews.com>，

David Warner< da ****** @ westbase.com>写道：

In article <da****************************@corp.supernews.com >,
David Warner <da******@westbase.com> wrote:

我需要编写一些C代码来决定从stdin读取或从argv获取文件名并进行处理。
我已经尝试了从getc，getchar，read，gets，
等我能想到的一切。一切都行不通。我在返回值上测试EOF或NULL
并且程序只是在终端读取时挂起。

I need to write some C code that will decide between either reading from
stdin or take a file name from argv and process it. I have tried everything I can think of from getc, getchar, read, gets,
etc. which all did not work. I test for EOF or NULL on the return values
and the program just hangs on a terminal read.

通常要做的就是看看是否存在''文件名参数

如果没有，则从stdin读取。尝试阅读是没用的，因为

stdin上总会有文件或终端（对于典型的

操作系统）。


- Richard

The usual thing to do it to see whether there''s a filename argument
and read from stdin if there isn''t. Trying to read is useless, since
there will always be either a file or a terminal on stdin (for typical
operating systems).

-- Richard