如何将utf16 ushort数组转换为utf8 std :: string？

问题描述

目前我正在写一个插件，它只是一个现有库的包装。
插件的主机传递给我一个utf-16格式的字符串，定义如下

typedef unsigned short PA_Unichar;

并且包裹的库只接受一个const char *或一个std :: string utf-8格式化的字符串
我试着编写一个转换函数

  std :: string toUtf8（const PA_Unichar * data）
 {
 std :: wstring_convert< std :: codecvt_utf8_utf16< char16_t>，char16_t>兑换; 
 return std :: string（convert.to_bytes（static_cast< const char16_t *>（data））; 
} 
  

但是显然这不起作用，引发了一个编译错误static_cast从'const指针'（也称为'const unsigned short *'）''不允许'const char16_t *' / p>

那么，最优雅/正确的方法是什么？

解决方案

您可以将 PA_unichar 字符串转换为使用 basic_string（Iterator，Iterator）构造函数，然后使用 std :: codecvt_utf8_utf16 facet：

  std :: string conv（const PA_unichar * str，size_t len）
 {
 std :: u16string s（str，str + len）; 
 std :: wstring_convert< std :: codecvt_utf8_utf16< char16_t>，char16_t> convert; 
 return convert.to_bytes（s）; 
} 
  

我认为测试这个，因为我的实现不支持它。我有一个实现 wstring_convert ，我计划包括在GCC 4.9，但我没有 codecvt_utf8_utf16 以测试它。

Currently I'm writing a plugin which is just a wrapper around an existing library.The plugin's host passes to me an utf-16 formatted string defined as following

typedef unsigned short PA_Unichar;

And the wrapped library accepts only a const char* or a std::string utf-8 formatted stringI tried writing a conversion function like

std::string toUtf8(const PA_Unichar* data)
{
std::wstring_convert<std::codecvt_utf8_utf16<char16_t>,char16_t> convert;
return std::string(convert.to_bytes(static_cast<const char16_t*>(data));
}

But obviously this doesn't work, throwing me a compile error "static_cast from 'const pointer' (aka 'const unsigned short*') to 'const char16_t *' is not allowed"

So what's the most elegant/correct way to do it?

Thank you in advance.

解决方案

You could convert the PA_unichar string to a string of char16_t using the basic_string(Iterator, Iterator) constructor, then use the std::codecvt_utf8_utf16 facet as you attempted:

std::string conv(const PA_unichar* str, size_t len)
{
  std::u16string s(str, str+len);
  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>,char16_t> convert;
  return convert.to_bytes(s);
}

I think that's right. Unfortunately I can't test this, as my implementation doesn't support it yet. I have an implementation of wstring_convert which I plan to include in GCC 4.9, but I don't have an implementation of codecvt_utf8_utf16 to test it with.

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