Conversion of std::wstring to QString throws linker error

Question

Hi I need to convert a std::wstring to QString and I tried the most obvious way of

std::wstring wideString;
QString qtString = QStri         


        

Answer 1

boost::filesystem::path also seems to require the project setting "treat wchar as built-in type = yes", so vahapt's solution was the only one I could get to work.

Answer 2

Edit your Visual Studio project settings and under C/C++ -> Language set the option Treat wchar_t was Built-in Type to No.

Answer 3

Best solution to the problem is to set the option "Treat wchar_t was Built-in Type" to No. However in some cases this might not be possible.

For example xerces_c is compiled with wchar_t as Built-in Type. If you need to use both xerces_c then you must either recompile QT or xerces_c to match a common Built-in Type setting.

Windows uses UTF16 charset so does QT for unicode strings. Thus, the alternative solution below might be a life saver.

/*! Convert a QString to an std::wstring */
std::wstring qToStdWString(const QString &str)
{
#ifdef _MSC_VER
    return std::wstring((const wchar_t *)str.utf16());
#else
    return str.toStdWString();
#endif
}

/*! Convert an std::wstring to a QString */
QString stdWToQString(const std::wstring &str)
{
#ifdef _MSC_VER
    return QString::fromUtf16((const ushort *)str.c_str());
#else
    return QString::fromStdWString(str);
#endif
}

Answer 4

This even may happen if QtCore4.lib is linked correctly. Make sure that the VS option "Treat wchar_t as built in type" is turned OFF.

Answer 5

Add

QT += core

to you .pro file. This results in what the other answer tell you to do. (be sure to rerun qmake)

Answer 6

I was seeing a similar problem but none of these solutions worked. I eventually realised I was compiling with Visual Studio 2017 but linking to Qt compiled with Visual Studio 2013. Once I selected the right version it worked fine.