如何将ASCII和BINARY数据同时写入同一个文件 [英] How to write ASCII and BINARY data to the same file at the same time

问题描述

我的输出使用VTK数据类型。由于我的数据变得越来越大，需要花费相当多的时间才能用ASCII编写，这就是我迄今为止所做的。

我需要将其更改为二进制格式，但问题是文件有一些标题（见 http：//www.vtk .org / VTK / img / file-formats.pdf ），即使是二进制文件，也需要用ASCII编写。

现在我没有足够的二进制格式的经验，我第一次尝试是通过

  ofstream asciiWriter（file_name.c_str（））打开两个流; 
 ofstream binWriter（file_name.c_str（），ios :: app | ios :: binary）; 
  

问题是输出看起来杂乱无章， asciiWriter 和 binWriter 没有以正确的顺序输出，所以我不能在ParaView中后处理我的文件。我试过的一件事就是每当我完成，使用 asciiWriter.flush（）和 binWriter.flush（）标题/数据写入，但这也没有帮助。

我应该怎么做？
$ b

PS：不想使用VTK包本身...它的巨大并增加了我的代码依赖！

解决方案

在所有现代系统我知道，二进制和文本文件的唯一区别在于C运行时库处理换行符和文件结束符。具体而言，在* nix系统上，文本和二进制文件的行为完全相同。在Windows上，向文本文件写入'\ n'会导致'\r'然后将'\ n'（LF）写入实际文件;阅读\r\\\
对显示为单个'\ n'。在Windows上，从文本文件中读取'\x1A'（Ctrl-Z，EOF）则表示文件结束状态。二进制文件是逐字读取和写入的，没有转换。

读取你的文档，我注意到它指定了'\\\
'\r\\\
）在行尾。这表明，正确的方法是读取和写入的头文件，即使在Windows上的二进制文件。

作为一个无关紧要，一些旧系统（RSX-11和VMS想起来）有二进制文件，这些文件与文本文件在磁盘上非常不同。他们还直接在操作系统中支持基于记录和索引的文件。但是，他们修改了 open（）， fopen（）等函数的修改版本（以及其他语言）来处理打开文件时可能指定的过多的参数。在这样的系统上，每次都必须使用正确的文件模式。

I work with a VTK data type for my outputs. Since my data is becoming larger and larger, it's taking considerable time to write it in ASCII and that's what I have been doing so far.

I need to change that into binary format but the problem is the file has some headers (see http://www.vtk.org/VTK/img/file-formats.pdf) that need to be written in ASCII even for binary files.

Now I don't have enough experience with binary formats and my first try was to open two streams via

ofstream asciiWriter(file_name.c_str());
ofstream binWriter(file_name.c_str(), ios::app | ios::binary);

problem is the output seems to be disorganized and asciiWriter and binWriter are not outputting in the correct order and so I cannot post-process my file in ParaView. One thing I tried was to use asciiWriter.flush() and binWriter.flush() whenever I'm done with header/data writing but that does not help either.

What should I do?

PS: I do not want to use the VTK package itself ... its HUGE and adds to my code dependency!

解决方案

On all modern systems that I know of, the only difference between binary and text files is the treatment of newlines and end-of-file characters by the C runtime library. Specifically, on *nix systems, text and binary files behave exactly the same. On Windows, writing a '\n' to a text file causes a '\r' (CR) followed by a '\n' (LF) to be written to the actual file; reading a "\r\n" pair shows up as a single '\n'. Also on Windows, reading a '\x1A' (Ctrl-Z, EOF) from a text file signals the end-of-file condition. Binary files are read and written verbatim, with no conversion.

Reading your document, I notice that it specifies '\n' only (not "\r\n") at the end of the lines. That suggests that the correct approach is to read and write the header as a binary file, even on Windows.

As an irrelevant aside, some older systems (RSX-11 and VMS come to mind) had binary files that were wildly different, on disk, from text files. They also supported record-based and indexed files directly in the OS. However, they had modified versions of the open(), fopen() etc functions (and the equivalents in other languages) to handle the plethora of arguments that could be specified when opening a file. On such a system, you had to use the correct file mode every time.

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