How to read UTF-8 text from file using Qt?

Question

I have some problems with reading UTF-8 encoded text from file. My version reads only ASCII characters.

#include <QtCore>

int main()
{
    QFile file("s.txt");

    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        return -1;
    }

    QTextStream in(&file);
    while(!in.atEnd())
    {
        QString line = in.readLine();
        qDebug() << line;
    }
}

s.txt:

jąkać się
ślimak
śnieżyca

output:

"jka si" 
"limak" 
"nieyca"

What should I use?

score 31 · Accepted Answer · edited Oct 11 '19 at 09:57

31

See QTextStream::setCodec():

in.setCodec("UTF-8");

edited Oct 11 '19 at 09:57

bunto1

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4
15

answered Apr 12 '11 at 03:42

John Flatness

32,469
5
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I tried it and now all the non-ASCII characters are replaced with "?". – Maciej Ziarko Apr 12 '11 at 03:49
Perhaps your qDebug output console doesn't support those characters. That'd be a reasonable source of the "?". Try showing the string in a QLabel on-screen. – edA-qa mort-ora-y Apr 12 '11 at 03:52
It's not the issue. dDebug() << QString("śnieżyca"); works perfectly. – Maciej Ziarko Apr 12 '11 at 03:53
You're sure your input file is actually UTF-8? – John Flatness Apr 12 '11 at 04:01
4 text editors (Geany, jEdit, gedit, Kate) say it is UTF-8. And still I have my problem with "?". – Maciej Ziarko Apr 12 '11 at 05:01
OK, it eventually fixed my problem. Thanks! – Maciej Ziarko Apr 18 '11 at 16:23

Yi Zhao · Answer 2 · 2011-04-12T05:36:39.250

6

You shuold do:

QTextStream in(&file);
in.setCodec("UTF-8"); // change the file codec to UTF-8.

while(!in.atEnd())
{
    QString line = in.readLine();
    qDebug() << line.toLocal8Bit(); // convert to locale multi-byte string 
}

edited Apr 12 '11 at 05:36

answered Apr 12 '11 at 03:50

Yi Zhao

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After it I get: "j?ka? si?" "?limak" "?nie?yca" – Maciej Ziarko Apr 12 '11 at 03:51
1

What's your default locale? If `qDebug() << QString("śnieżyca");` works perfectly, it means your system configured a non-ASCII locale. You should try `qDebug() << line.toLocal8Bit();` – Yi Zhao Apr 12 '11 at 05:33

score 2 · Answer 3 · answered Dec 20 '16 at 14:59

2

I was also having ???? when reading an XML file with QXmlStreamReader. I fixed it by calling this before reading the file:

QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));

answered Dec 20 '16 at 14:59

laurent

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How to read UTF-8 text from file using Qt?

3 Answers3