no suitable user-defined conversion from utility::string_t to std::string

问题

I am using the casablanca C++ Rest library to make HTTP requests.

The problem is that this gives a utility::string_t string as output and I can't quite find any way to convert this to a classic std::string. Any ideas?

client.request(methods::GET).then([](http_response response)
{
  if(response.status_code() == status_codes::OK)
  {
    string_t s = response.extract_string().get();
  }
});

回答1:

If you see the documentation for C++ REST SDK from github, you'll find a typedef

C++ Rest SDK - utility Namespace Reference

typedef std::string     string_t;

So no need to convert it. Both are same types.

回答2:

Depending on what platform you are compiling for, the utility::string_t type will be typedef'd to either std::wstring (on Windows) or std::string (on Linux/OSX).

To get a classic utf-8 std::string regardless of platform, take a look at utility::conversions::to_utf8string.

reference documentation

回答3:

On Windows Phone 8.1 there is this define:

typedef std::wstring     string_t;

I used this:

string_t toStringT = U("sample");
std::string fromStringT(toStringT.begin(), toStringT.end());

or:

std::string fromStringT(conversions::to_utf8string(toStringT));

来源：https://stackoverflow.com/questions/31264974/no-suitable-user-defined-conversion-from-utilitystring-t-to-stdstring