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ToStdWStringAndBuiltInWchar: Difference between revisions
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'''English''' [[toStdWStringAndBuiltInWchar | '''English''' [[toStdWStringAndBuiltInWchar SimplifiedChinese|简体中文]]<br />[[Category:HowTo]]<br />[[Category:snippets]] | ||
=QString, std::wstring and built-in wchar_t= | = QString, std::wstring and built-in wchar_t = | ||
==Problem statement== | == Problem statement == | ||
Qt advises to build your Qt based software without wchar_t as built-in type, just like the Qt libraries themselves. In some cases this is not desired by the environment or not possible because other libraries have been built with the built-in wchar_t type. This will cause obscure linker errors when using std::wstrings, and | Qt advises to build your Qt based software without wchar_t as built-in type, just like the Qt libraries themselves. In some cases this is not desired by the environment or not possible because other libraries have been built with the built-in wchar_t type. This will cause obscure linker errors when using std::wstrings, and "QString::toStdWString()":http://doc.qt.io/qt-5.0/qtcore/qstring.html#toStdWString and "QString::fromStdWString()":http://doc.qt.io/qt-5.0/qtcore/qstring.html#fromStdWString. | ||
==Possible solution== | == Possible solution == | ||
Windows uses utf-16 for its character encoding, as does Qt. Using this information we can use the following code to work around the issue: | Windows uses utf-16 for its character encoding, as does Qt. Using this information we can use the following code to work around the issue: | ||
<code>/*! Convert a QString to an std::wstring '''/<br />std::wstring qToStdWString(const QString &str)<br />{<br />#ifdef _MSC_VER<br /> return std::wstring((const wchar_t''')str.utf16());<br />#else<br /> return str.toStdWString();<br />#endif<br />} | |||
/*! Convert an std::wstring to a QString '''/<br />QString stdWToQString(const std::wstring &str)<br />{<br />#ifdef _MSC_VER<br /> return QString::fromUtf16((const ushort''')str.c_str());<br />#else<br /> return QString::fromStdWString(str);<br />#endif<br />}</code> | |||
Revision as of 10:05, 24 February 2015
English 简体中文
QString, std::wstring and built-in wchar_t
Problem statement
Qt advises to build your Qt based software without wchar_t as built-in type, just like the Qt libraries themselves. In some cases this is not desired by the environment or not possible because other libraries have been built with the built-in wchar_t type. This will cause obscure linker errors when using std::wstrings, and "QString::toStdWString()":http://doc.qt.io/qt-5.0/qtcore/qstring.html#toStdWString and "QString::fromStdWString()":http://doc.qt.io/qt-5.0/qtcore/qstring.html#fromStdWString.
Possible solution
Windows uses utf-16 for its character encoding, as does Qt. Using this information we can use the following code to work around the issue:
/*! Convert a QString to an std::wstring '''/<br />std::wstring qToStdWString(const QString &str)<br />{<br />#ifdef _MSC_VER<br /> return std::wstring((const wchar_t''')str.utf16());<br />#else<br /> return str.toStdWString();<br />#endif<br />}
/*! Convert an std::wstring to a QString '''/<br />QString stdWToQString(const std::wstring &str)<br />{<br />#ifdef _MSC_VER<br /> return QString::fromUtf16((const ushort''')str.c_str());<br />#else<br /> return QString::fromStdWString(str);<br />#endif<br />}