C++ 将 Unicode UTF-8 文件读入 wstring
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Read Unicode UTF-8 file into wstring
提问by Abdelwahed
How can I read a Unicode (UTF-8) file into wstring(s) on the Windows platform?
如何wstring在 Windows 平台上将Unicode (UTF-8) 文件读入(s) 中？
回答by LihO
With C++11 support, you can use std::codecvt_utf8 facetwhich encapsulates conversion between a UTF-8 encoded byte string and UCS2 or UCS4 character stringand which can be used to read and write UTF-8 files, both text and binary.
随着C ++ 11的支持，你可以使用的std :: codecvt_utf8方面它封装了一个UTF-8编码的字节串和UCS2或UCS4字符串之间的转换，并可以用来读取和写入UTF-8文件，文本和二进制.
In order to use facetyou usually create locale objectthat encapsulates culture-specific information as a set of facets that collectively define a specific localized environment.Once you have a locale object, you can imbueyour stream buffer with it:
为了使用facet，您通常会创建locale 对象，该对象将特定于文化的信息封装为一组共同定义特定本地化环境的 facet。一旦你有了一个语言环境对象，你就可以用它来填充你的流缓冲区：
#include <sstream>
#include <fstream>
#include <codecvt>
std::wstring readFile(const char* filename)
{
std::wifstream wif(filename);
wif.imbue(std::locale(std::locale::empty(), new std::codecvt_utf8<wchar_t>));
std::wstringstream wss;
wss << wif.rdbuf();
return wss.str();
}
which can be used like this:
可以这样使用：
std::wstring wstr = readFile("a.txt");
Alternatively you can set the global C++ localebefore you work with string streams which causes all future calls to the std::localedefault constructor to return a copy of the global C++ locale(you don't need to explicitly imbue stream buffers with it then):
或者，您可以在使用字符串流之前设置全局 C++ 语言环境，这会导致所有未来对std::locale默认构造函数的调用返回全局 C++ 语言环境的副本（然后您不需要显式地将其注入流缓冲区）：
std::locale::global(std::locale(std::locale::empty(), new std::codecvt_utf8<wchar_t>));
回答by Philipp
According to a comment by @Hans Passant, the simplest way is to use _wfopen_s. Open the file with mode rt, ccs=UTF-8.
根据@Hans Passant 的评论，最简单的方法是使用_wfopen_s。用 mode 打开文件rt, ccs=UTF-8。
Here is another pure C++ solution that works at least with VC++ 2010:
这是另一个至少适用于 VC++ 2010 的纯 C++ 解决方案：
#include <locale>
#include <codecvt>
#include <string>
#include <fstream>
#include <cstdlib>
int main() {
const std::locale empty_locale = std::locale::empty();
typedef std::codecvt_utf8<wchar_t> converter_type;
const converter_type* converter = new converter_type;
const std::locale utf8_locale = std::locale(empty_locale, converter);
std::wifstream stream(L"test.txt");
stream.imbue(utf8_locale);
std::wstring line;
std::getline(stream, line);
std::system("pause");
}
Except for locale::empty()(here locale::global()might work as well) and the wchar_t*overload of the basic_ifstreamconstructor, this should even be pretty standard-compliant (where “standard” means C++0x, of course).
除了locale::empty()（这里locale::global()也可以工作）和构造函数的wchar_t*重载之外basic_ifstream，这甚至应该是非常符合标准的（其中“标准”当然是指 C++0x）。
回答by AshleysBrain
Here's a platform-specific function for Windows only:
这是仅适用于 Windows 的特定于平台的功能：
size_t GetSizeOfFile(const std::wstring& path)
{
struct _stat fileinfo;
_wstat(path.c_str(), &fileinfo);
return fileinfo.st_size;
}
std::wstring LoadUtf8FileToString(const std::wstring& filename)
{
std::wstring buffer; // stores file contents
FILE* f = _wfopen(filename.c_str(), L"rtS, ccs=UTF-8");
// Failed to open file
if (f == NULL)
{
// ...handle some error...
return buffer;
}
size_t filesize = GetSizeOfFile(filename);
// Read entire file contents in to memory
if (filesize > 0)
{
buffer.resize(filesize);
size_t wchars_read = fread(&(buffer.front()), sizeof(wchar_t), filesize, f);
buffer.resize(wchars_read);
buffer.shrink_to_fit();
}
fclose(f);
return buffer;
}
Use like so:
像这样使用：
std::wstring mytext = LoadUtf8FileToString(L"C:\MyUtf8File.txt");
Note the entire file is loaded in to memory, so you might not want to use it for very large files.
请注意，整个文件已加载到内存中，因此您可能不想将其用于非常大的文件。
回答by Shen Yu
#include <iostream>
#include <fstream>
#include <string>
#include <locale>
#include <cstdlib>
int main()
{
std::wifstream wif("filename.txt");
wif.imbue(std::locale("zh_CN.UTF-8"));
std::wcout.imbue(std::locale("zh_CN.UTF-8"));
std::wcout << wif.rdbuf();
}
回答by ThomasMcLeod
This question was addressed in Confused about C++'s std::wstring, UTF-16, UTF-8 and displaying strings in a windows GUI. In sum, wstring is based upon the UCS-2 standard, which is the predecessor of UTF-16. This is a strictly two byte standard. I believe this covers Arabic.
这个问题在Confused about C++'s std::wstring, UTF-16, UTF-8 and display strings in a windows GUI 中得到解决。总之，wstring 基于 UCS-2 标准，它是 UTF-16 的前身。这是一个严格的两字节标准。我相信这涵盖了阿拉伯语。
回答by dlchambers
This is a bit raw, but how about reading the file as plain old bytes then cast the byte buffer to wchar_t* ?
这有点原始，但是如何将文件作为普通旧字节读取然后将字节缓冲区转换为 wchar_t* ？
Something like:
就像是：
#include <iostream>
#include <fstream>
std::wstring ReadFileIntoWstring(const std::wstring& filepath)
{
std::wstring wstr;
std::ifstream file (filepath.c_str(), std::ios::in|std::ios::binary|std::ios::ate);
size_t size = (size_t)file.tellg();
file.seekg (0, std::ios::beg);
char* buffer = new char [size];
file.read (buffer, size);
wstr = (wchar_t*)buffer;
file.close();
delete[] buffer;
return wstr;
}
