TCHAR to QString

Hello,

I need to convert a TCHAR to QString. He solutions I found do not work. I have:

TCHAR chError[2048];
I tried
 QString strError = QString::fromUtf16(chError);

But compiler said:  Fehler: C2664: 'QString::fromUtf16' : cannot convert parameter 1 from 'TCHAR [2048]' to 'const ushort *'

Any idea?

Ingo
Ingo FoersterProgrammerAsked:
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jkrCommented:
Again, that will depend on whether your project is built as ANSI or UNICODE. I'd suggest a helper wrapper similar to the one in your last wuestion, e.g.

QString QStringFromTCHAR(const TCHAR* p) {

  QString qs;

#ifdef _UNICODE
  qs = QString::fromStdWString(std::string(p));
#else
  qs = QString::fromStdWString(std::string(p));
#endif

  return qs;
}

// ...

TCHAR chError[2048];
 QString strError = QStringFromTCHAR(chError);

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sarabandeCommented:
But compiler said:  Fehler: C2664: 'QString::fromUtf16' : cannot convert parameter 1 from 'TCHAR [2048]' to 'const ushort *'

if UNICODE macro is not defined the TCHAR[2048] is char[2048] and the conversion would work if you simply initialize the QString with the char string cause QString has a constructor that takes a const char *:

QString strError = chError;

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but if UNICODE is defined the initialization fails since QString accepts  'unsigned short*' while wchar_t is 'signed' and an own type, which means it can only converted to short or unsigned short by doing an explicit cast though both wchar_t and short are 16-bit integers.

that is all very bad and the conversion could only be done by

QString strError = (const ushort*)chError;

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or

QString strError = reinterpret_cast<const ushort*>chError;

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what both is not very convenient.

jkr showed how you could use std::string and std::wstring as a helper (in the second block there is a typo and std::wstring was meant) but actually this is also not very elegant especially if it still is based on the TCHAR wich you can't use anyhow (see your other question).

so i would recommend to using class QChar and QString wherever it is possible and only convert to wchar_t or wstring when there is no alternative. a normal c cast as with

QString qs = "somewhat";
...
std::wstring ws = (const wchar_t*)qs.utf16();

probably is the easiest and most transparent way.

or you define helpers W2US, CW2CUS and US2W, CUS2CW which do the job

unsigned short * W2US(wchar_t* ws) { return (unsigned short*)ws); }
const unsigned short * CW2CUS(const wchar_t* ws) { return (const unsigned short*)ws); }
wchar_t * US2W(unsigned short* us) { return (wchar_t*)us); }
const wchar_t CW2CUS(const unsigned short* us) { return (const wchar_t*)us); }

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Sara
Ingo FoersterProgrammerAuthor Commented:
Hi,
I use now: QString::fromWCharArray(chError)
works well.

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sarabandeCommented:
good.

since you couldn't do the T-switch from UTF16 to char with that code, i would recommend not using the T types like TCHAR, LPCTSTR but using the c++ equivalents wchar_t, const wchar_t *, ... at least for new code. you also could use WCHAR, LPCWSTR, ... what is equivalent but again proprietary to MS and therefore less recommendable.

Sara
Ingo FoersterProgrammerAuthor Commented:
I develop on MAC so I cannot use MS formats.  It seems the library I used was developed on MS so I always have to convert in many places.
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