如何打开一个std :: fstream（ofstream或ifstream）与unicode文件名？ [英] How to open an std::fstream (ofstream or ifstream) with a unicode filename?

问题描述

你不会想象一些基本的东西，如使用C ++标准库为Windows应用程序打开一个文件是棘手的...但似乎是。通过Unicode这里我的意思是UTF-8，但我可以转换为UTF-16或任何，点是从Unicode文件名得到一个流实例。在我解决自己的解决方案之前，有没有首选的路线？特别是跨平台的？

解决方案

C ++标准库不支持Unicode。 char 和 wchar_t 不需要是Unicode编码。

在Windows上， wchar_t 是UTF-16，但是没有直接支持标准库中的UTF-8文件名（ char datatype在Windows上不是Unicode）

对于MSVC（因此是Microsoft STL），提供了filestreams的构造函数， > const wchar_t * filename，可以创建流：

  wchar_t const name [ = Lfilename.txt; 
 std :: fstream file（name）;但是，这种重载不是由C ++ 11标准规定的（它只保证存在一个基于 char 的版本）。它也不存在于替代的STL实现，如GCC的libstdc ++对于MinGW（-w64），版本g ++ 4.8.x。
 
 
 
注意，就像 char 在Windows上不是UTF8，在其他操作系统 wchar_t 可能不是UTF16。所以总体来说，这不太可能是便携式的。打开一个给定 wchar_t 文件名的流不是根据标准定义的，并且在 char 中指定文件名困难，因为char使用的编码在OS之间变化。
 
You wouldn't imagine something as basic as opening a file using the C++ standard library for a Windows application was tricky ... but it appears to be. By Unicode here I mean UTF-8, but I can convert to UTF-16 or whatever, the point is getting an ofstream instance from a Unicode filename. Before I hack up my own solution, is there a preferred route here ? Especially a cross-platform one ?
解决方案
The C++ standard library is not Unicode-aware. char and wchar_t  are not required to be Unicode encodings.

On Windows, wchar_t is UTF-16, but there's no direct support for UTF-8 filenames in the standard library (the char datatype is not Unicode on Windows)

With MSVC (and thus the Microsoft STL), a constructor for filestreams is provided which takes a const wchar_t* filename, allowing you to create the stream as:
wchar_t const name[] = L"filename.txt";
std::fstream file(name);
However, this overload is not specified by the C++11 standard (it only guarantees the presence of the char based version). It is also not present on alternative STL implementations like GCC's libstdc++ for MinGW(-w64), as of version g++ 4.8.x.

Note that just like char on Windows is not UTF8, on other OS'es wchar_t may not be UTF16. So overall, this isn't likely to be portable. Opening a stream given a wchar_t filename isn't defined according to the standard, and specifying the filename in chars may be difficult because the encoding used by char varies between OS'es.

                        
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