[Qt-interest] Non-latin characters in QString and char * on Windows

[Thiago Macieira]

On Wednesday, 2 de March de 2011 23:05:25 Konstantin Tokarev wrote:
> Hi all,
> 
> I need to convert QString, containg non-latin characters (specifically,
> cyrillic) to const char *, in order to open file with ifstream (requirement
> of 3rd party library). One may think that it's about
> QString::toLocal8Bit(), but it does not help on Windows!

It does, but you have to write proper code to get it.

You've been caught in a simple mistake that happens to many people:
    const char * fileNameStr = fileName.toLocal8Bit().constData();

Ask yourself: who owns this pointer that you got? Is it the QString? If it is, 
can you point me to any method in QString that return a const char * in the 
local 8-bit encoding?

The answer is that the QByteArray owns it.

Which QByteArray you may ask? THAT is the problem. When you figure out where 
the QByteArray is, you'll have solved the problem.

Anyway, the recommended way to encode a filename from QString to 8-bit is to 
use QFile::encodeName.

> See attached program. On Linux with UTF-8 everything works fine with either
> toUtf8 or toLocal8Bit. On Windows (default encoding is CP1251) both
> functions return crap (different between each other). Of course, ifstream
> cannot open corrupted file paths.
> 
> How to get proper representation of QString fileName in const char * ?
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
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