文件中的反向迭代器 [英] Reverse iterator in file

问题描述

大家好，

如何使用文件流反向迭代器从结束位置到开始位置读取文件?

有人回答我的问题............

Hello to all,

How to read the file from end position to beginning position using file stream reverse iterator?

Anybody answer my question............

推荐答案

我想到的获得istream_reverse_iterator的最快方法是使用普通的istream_iterator，但为基于它的流实现您自己的流缓冲区.

看看Kreft和Langer的"Standard C ++ Streams and Locales"，了解iostream库的所有细节，以及为什么想要的东西有些棘手.它还会告诉您如何实现自己的流缓冲区，以帮助您摆脱这些情况.

干杯，

Ash

The quickest way I can think of to get a istream_reverse_iterator would be to use an ordinary istream_iterator but implement your own stream buffer for the stream you''re basing it on.

Have a look at Kreft and Langer''s "Standard C++ Streams and Locales" for all the gory details of the iostream libraries and why what you want is a bit tricky. It''ll also tell you how to implement your own stream buffers to help you out of these situations.

Cheers,

Ash

非专业解决方案:):

A non-professional solution :) :

class mybuffer: public basic_filebuf<char>
{
public:
  char* Beg() { return gptr(); }
  char* End() { return egptr(); }
};

int _tmain(int argc, _TCHAR* argv[])
{
  std::ifstream file;
  file.open(_T("d:\\test.txt"));
  
  mybuffer* Buf = (mybuffer*) file.rdbuf(); // a "way" to the protected methods
  Buf->sgetc(); // a "way" to fill the buffer (the file will be read)

  char* pCharBeg = Buf->Beg();
  char* pCharEnd = Buf->End();

  reverse_iterator<char*> rIter(pCharEnd);

  while (pCharBeg <= &(*rIter)) {
    cout << *(rIter++);
  }

  file.close();
  
  return getchar();
}

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