从LPCWSTR转换为LPCSTR [英] Converting from LPCWSTR to LPCSTR

问题描述

我有麻烦试图施放一个LPCWSTR到一个LPCSTR。

I'm having trouble trying to cast a LPCWSTR to an LPCSTR.

的背景

我编程一个VC ++ 2010应用程序，并已运行到哪里，我不得不从式系统转换的情况::字符串^到std :: string的。我用这个code这样做的：

I am programming a VC++ 2010 application, and have already run into the situation where I had to convert from type System::String^ to std::string. I used this code to do so:

private: std::string toss(System::String^ s)
    {
        msclr::interop::marshal_context context;
        return context.marshal_as<std::string>(s);
    }

这样做，我想我会解决我所有的问题。我错了。由此，我需要转换为std :: string作为LPCSTR，一些Windows API的使用。

Doing so, I thought I would solve all my problems. I was wrong. From this, I need to cast a std::string as an LPCSTR, to use with some Windows API.

读了一些存在的问题上做之后，我觉得我卡住了。我被告知使用方法：

After reading some of the existing questions on SO, I feel like I am stuck. I was told to use:

LPCSTR str = existingstr.c_str();

当我用这个，但我给出的错误：无法从LPCWSTR转换为LPCSTR

When I use this, however, I am given the error: Cannot convert from LPCWSTR to LPCSTR

有没有人有一个更好的主意是我应该做的这种特殊情况下，或如何，我可以从LPCWSTR转换为LPCSTR？

Does anyone have a better idea of what I should do in this specific case, or how I can convert from LPCWSTR to LPCSTR?

在此先感谢。

推荐答案

编辑：完全误解了问题，所以不顾我前面的回答，抱歉。如果你需要这个字符串后面传递到一个Windows API，你有充分的理由使用std :: string的，而不是标准:: wstring的？

completely misread the question so disregard my earlier answer, sorry. If you need to later pass this string into a Windows API, do you have a reason for using std::string and not std::wstring?

其他编辑：有在这里我而言有些混乱。什么是existingstr的类型，什么是Windows API函数你打电话的签名？我认为，这将有助于明确的东西。如果existingstr为std :: string的，然后.cstr（）是LPCSTR兼容（即字符常量*）。如果existingstr为std :: wstring的，事实并非如此。是API以LPCSTR或LPCWSTR？

Additional edit: there's some confusion on my part here. What is the type of existingstr and what is the signature of the Windows API function you're calling? I think that would help clear things up. If existingstr is std::string, then .cstr() is compatible with LPCSTR (i.e. char const*). If existingstr is std::wstring, it is not. Is the API taking LPCSTR or LPCWSTR?

您可以用这个来代替：

private: std::wstring toss(System::String^ s)
{
   std::wstring result;
   {
       pin_ptr<wchar_t const> ptr = PtrToStringChars(s);
       result = ptr;
   }
   return result;
}

.c_str（）在一个std :: wstring的会导致在wchar_t常量*（即LPCWSTR）。

.c_str() on a std::wstring would result in a wchar_t const* (i.e. a LPCWSTR).

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