在C ++中部分截断流（fstream或ofstream） [英] Partially truncating a stream (fstream or ofstream) in C++

问题描述

我试图使用fstream部分截断（或缩短）现有文件。我已经尝试写一个EOF字符，但这似乎什么也不做。

I am trying to partially truncate (or shorten) an existing file, using fstream. I have tried writing an EOF character, but this seems to do nothing.

任何帮助将被赞赏...

Any help would be appreciated...

推荐答案

我不认为你可以。有许多函数用于向上和向下移动 HANDLE < - > int < - > FILE * 的包装层次结构，至少在Windows上，但没有适当从iostreams对象中提取 FILE * （如果确实是用一个实现的话）。

I don't think you can. There are many functions for moving "up and down" the wrapper hierarchy for HANDLE<->int<->FILE *, at least on Windows, but there is no "proper" to extract the FILE * from an iostreams object (if indeed it is even implemented with one).

您可能会发现此问题是您的帮助。

You may find this question to be of assistance.

我个人强烈建议你避开iostreams，他们设计不好，C ++很重，看起来很讨厌。查看 Boost的iostreams ，或换行 stdio.h （如果您需要使用课程）。

Personally I would strongly recommend steering clear of iostreams, they're poorly designed, heavily C++, and nasty to look at. Take a look at Boost's iostreams, or wrap stdio.h if you need to use classes.

stdio的相关功能是 ftruncate（）。

The relevant function for stdio is ftruncate().

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