C/C++ 调用标准库函数实现 std::string to std::wstring 相互字符集变换（转）

#include <locale>
#include <codecvt>
#include <string>
#include <vector>
 
#if _MSC_VER >= 1600
#pragma execution_character_set("utf-8")
#endif
 
std::wstring utf8_to_wstring(const std::string& s) {
    std::wstring_convert<std::codecvt_utf8<wchar_t>> converter;
    return converter.from_bytes(s);
}
 
std::string wstring_to_utf8(const std::wstring& s) {
    std::wstring_convert<std::codecvt_utf8<wchar_t>> converter;
    return converter.to_bytes(s);
}
 
std::wstring ascii_to_wstring(const std::string& s)
{
    std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
    return converter.from_bytes(s);
}
 
std::wstring ascii_to_wstring2(const std::string& s)
{
    std::size_t len = mbstowcs(NULL, s.data(), 0);
    if (len == 0 || len == std::string::npos)
    {
        return std::wstring();
    }
 
    std::vector<wchar_t> buf(len + 1);
    return std::wstring(buf.data(), mbstowcs(&buf[0], s.data(), buf.size()));
}
 
std::string wstring_to_ascii(const std::wstring& s)
{
    std::size_t len = wcstombs(NULL, s.data(), 0);
    if (len == 0 || len == std::string::npos)
    {
        return std::string();
    }
 
    std::vector<char> buf(len + 1);
    return std::string(buf.data(), wcstombs(&buf[0], s.data(), buf.size()));
}
 
int main(int argc, const char* argv[])
{
    setlocale(LC_ALL, "chs");
    _wsetlocale(LC_ALL, L"chs");
 
    wprintf(L"%s\n", ascii_to_wstring(wstring_to_ascii(L"中国")).data());
    return getchar();
}