使用二进制数据测试文件中的EOF [英] Testing for EOF in file with binary data

问题描述

问候！


我正在开发一个需要读取包含HP LaserJet PCL代码的lp

生成的打印文件的C应用程序。如果PCL包含二进制数据到

定义要在页面上打印的位图，无论是图标还是软字体

下载，EOF测试都会提前结束，而不是阅读整个

文件。如何绕过EOF测试而不检测文件中的EOF值

？我错过了什么吗？


更多数据：


如果打印文件只包含文本数据或没有位图

值，打印文件正确读取。


建议？


提前致谢！


David Warner

-

comp.lang.c.moderated - 审核地址： cl ** @ plethora.net - 您必须

在您的标题中有适当的新闻组行，以便查看您的邮件，

或主题行中方括号中的新闻组名称。对不起。

Greetings!

I am working on a C app that needs to read print files generated by lp
that contain HP LaserJet PCL codes. If the PCL contains binary data to
define a bit map to be printed on the page, either icon or soft-font
download, the EOF test ends prematurely and does not read the entire
file. How do I get around testing for EOF and not detect the EOF value
within the file? Am I missing something?

More Data:

If the print file just contains text data or does not have a bit map
value, the print file is read correctly.

Suggestions?

Thanks in advance!

David Warner
--
comp.lang.c.moderated - moderation address: cl**@plethora.net -- you must
have an appropriate newsgroups line in your header for your mail to be seen,
or the newsgroup name in square brackets in the subject line. Sorry.

推荐答案

[交叉发布删除]


David Warner写道：

[cross-posting deleted]

David Warner wrote:

我正在开发一个需要读取包含HP LaserJet PCL代码的lp
生成的打印文件的C应用程序。如果PCL包含二进制数据以定义要在页面上打印的位图，无论是图标还是软字体下载，EOF测试都会提前结束并且不会读取整个
文件。如何绕过EOF测试而不检测文件中的EOF值？我错过了什么吗？

I am working on a C app that needs to read print files generated by lp
that contain HP LaserJet PCL codes. If the PCL contains binary data to
define a bit map to be printed on the page, either icon or soft-font
download, the EOF test ends prematurely and does not read the entire
file. How do I get around testing for EOF and not detect the EOF value
within the file? Am I missing something?

我们更喜欢这个组中的std :: fstreams，但是相同的解决方案可以用C或C ++风格工作

文件流：使用文件大小而不是EOF

字符来确定您读取的数据量。您可以在C ++中使用

fstream :: seekg（）和fstream :: tellg（），或者使用等价物来获取该信息。

干杯！ --M

We prefer std::fstreams in this group, but the same solution can work
with C or C++ style file streams: use the file size rather than the EOF
character to determine how much data you read. You can use
fstream::seekg() and fstream::tellg() in C++ or the C equivalents to
get that info.

Cheers! --M

" mlimber" <毫升***** @ gmail.com>在留言中写道

news：11 ********************** @ g10g2000cwb.googlegr oups.com ......

"mlimber" <ml*****@gmail.com> wrote in message
news:11**********************@g10g2000cwb.googlegr oups.com...

[交叉发布删除]

David Warner写道：

[cross-posting deleted]

David Warner wrote:

我正在开发一个需要读取lp生成的打印文件的C app
包含HP LaserJet PCL代码。如果PCL包含二进制数据以定义要在页面上打印的位图，无论是图标还是软字体下载，EOF测试都会提前结束并且不会读取整个
文件。如何绕过EOF测试而不检测文件中的EOF值？我错过了什么？

I am working on a C app that needs to read print files generated by lp
that contain HP LaserJet PCL codes. If the PCL contains binary data to
define a bit map to be printed on the page, either icon or soft-font
download, the EOF test ends prematurely and does not read the entire
file. How do I get around testing for EOF and not detect the EOF value
within the file? Am I missing something?

我们更喜欢这个组中的std :: fstreams，但是相同的解决方案可以用C或C ++样式的文件流工作：使用文件大小而不是比EOF
字符确定你读取了多少数据。您可以在C ++中使用
fstream :: seekg（）和fstream :: tellg（），或者使用C等价物来获取该信息。

We prefer std::fstreams in this group, but the same solution can work
with C or C++ style file streams: use the file size rather than the EOF
character to determine how much data you read. You can use
fstream::seekg() and fstream::tellg() in C++ or the C equivalents to
get that info.

真正的答案是fgetc和朋友在int中的回报，

不是char。 EOF的值可以与您从二进制流中读取的任何char值区分开来。


PJ Plauger

Dinkumware，Ltd 。
http://www.dinkumware.com

在消息< Io ******************** @ giganews.com> ;,, PJ Plauger

< pj*@dinkumware.com>写道

In message <Io********************@giganews.com>, P.J. Plauger
<pj*@dinkumware.com> writes

" mlimber" <毫升***** @ gmail.com>在消息中写道
新闻：11 ********************** @ g10g2000cwb.googleg roups.com ...

"mlimber" <ml*****@gmail.com> wrote in message
news:11**********************@g10g2000cwb.googleg roups.com...

[交叉发布已删除]

David Warner写道：

[cross-posting deleted]

David Warner wrote:

我正在开发一个需要读取lp生成的打印文件的C应用程序
包含HP LaserJet PCL代码。如果PCL包含二进制数据以定义要在页面上打印的位图，无论是图标还是软字体下载，EOF测试都会提前结束并且不会读取整个
文件。如何绕过EOF测试而不检测文件中的EOF值？我错过了什么？

I am working on a C app that needs to read print files generated by lp
that contain HP LaserJet PCL codes. If the PCL contains binary data to
define a bit map to be printed on the page, either icon or soft-font
download, the EOF test ends prematurely and does not read the entire
file. How do I get around testing for EOF and not detect the EOF value
within the file? Am I missing something?

我们更喜欢这个组中的std :: fstreams，但是相同的解决方案可以用C或C ++样式的文件流工作：使用文件大小而不是比EOF
字符确定你读取了多少数据。你可以在C ++或C等价物中使用
fstream :: seekg（）和fstream :: tellg（）来获取那些信息。

We prefer std::fstreams in this group, but the same solution can work
with C or C++ style file streams: use the file size rather than the EOF
character to determine how much data you read. You can use
fstream::seekg() and fstream::tellg() in C++ or the C equivalents to
get that info.

真正的答案是fgetc和朋友在int中的回报，
不是char。 EOF的值可以与您从二进制流中读取的任何char值区分开来。

The real answer is that the return from fgetc and friends in an int,
not a char. The value of EOF is distinguishable from any char value
you read from a binary stream.

OP实际上并未明确表示他是否 ; EOF"意味着宏

或者只是文件结束条件的缩写，他实际上是比较一个字符与宏EOF的比较，或者他是否正在调用feof（）

函数？


在后一种情况下，第一个问题是：他实际打开了

文件吗？在二进制模式？在文本模式下，至少有一个操作系统

将控制-Z解释为文件结束并产生一个不成熟的
终止。 />

-

Richard Herring

The OP hasn''t actually made it clear whether his "EOF" means the macro
or is just an abbreviation for "end-of-file condition", Is he actually
comparing a char against the macro EOF, or is he calling the feof()
function?

In the latter case, the first question is: has he actually opened the
file in binary mode? In text mode, there''s at least one OS out there
that will interpret control-Z as end-of-file and produce a premature
termination.

--
Richard Herring

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