CODEWITHSUNDEEP
c++windowsqtunicode
adnan kamili
adnan kamili

Reputation: 9455

Special character not displaying properly in Qt 5

My app uses "μ" symbol in a label, in Qt4 it displays fine but in Qt 5 it doesn't for the same code. I am using following two lines at two different places where it works fine in Qt4 :

QChar('μ').toLatin1()

QString::fromUtf8(rateText.toLatin1()));

In second case the string contains the "μ" symbol.

In my main main.cpp, I have added following code:

#if (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
    QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
#else
    QTextCodec::setCodecForCStrings(QTextCodec::codecForName("UTF-8"));
#endif

Edit:

This line is enough in Qt 5 as Qt 5 uses utf-8 as default

 ui->timeLabel->setText("Time = "+rateText);  //rateText contains 'μ' symbol

But it doesn't work in Qt4, even this does not work

ui->timeLabel->setText("Time = "+rateText.toUtf8());

Only this worked for me:

ui->timeLabel->setText("Time = "+QString::fromUtf8(rateText.toLatin1()));

And I need a single solution which works across

Upvotes: 2

Views: 6027

Answers (1)

Frank Osterfeld
Frank Osterfeld

Reputation: 25155

 QString::fromUtf8(rateText.toLatin1()));

This doesn't make sense: you convert a string to latin1, just to the interpret the latin1 string as UTF8. You shouldn't do such conversions at all unless you explicitly need a QByteArray/const char*. toLatin1() will convert the micro sign to 0xb5, while the micro sign in UTF-8 would be 0xc2b5.

So instead of 

 QString foo = QString::fromUtf8(rateText.toLatin1()));

just do

 QString foo = rateText;

If you need to convert to byte array, make sure you convert back from the same encoding you converted to.

QByteArray ba = rateText.toUtf8();
... do stuff with ba
QString s = QString::fromUtf8(ba);

There should be only few occasions where this is needed though.

To track down encoding errors, I suggest to disable any implicit const char*/QByteArray <-> QString conversions via

DEFINES += QT_NO_CAST_FROM_ASCII QT_NO_CAST_TO_ASCII

Upvotes: 3

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