Unicode, linux, bash shell, printf

[sandor]

This must be really simple... I have a unicode QString and I would like to print the string to the shell (konsole, bash). The console has the appropriate characters so touch and mkdir can create unicode file names -> printing unicode characters must not be the problem. What I have:

QString s = "áéőűÁÉŐŰ";

QString s = "áéőűÁÉŐŰ";

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How do I print that string to the console that those characters appear?

[wysota]

What encoding that your console use?

[ChrisW67]

Your test string of eight "characters" is represented as the sixteen bytes (hex):

á     é     ő     ű     Á     É     Ő     Ű
C3 A1 C3 A9 C5 91 C5 B1 C3 81 C3 89 C5 90 C5 B0

á     é     ő     ű     Á     É     Ő     Ű
C3 A1 C3 A9 C5 91 C5 B1 C3 81 C3 89 C5 90 C5 B0

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when encoded as UTF-8 (which is the most likely thing your editor has done). Constructing or assigning a QString from char* uses fromAscii() which will be misinterpreting the bytes when converting to QString's internal 16-bit character format. Try this:

QString s = QString::fromUtf8("áéőűÁÉŐŰ");

QString s = QString::fromUtf8("áéőűÁÉŐŰ");

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[sandor]

Well, hmm, it does not quite work. Actually the problem is not how to put into QString, it is the easy part. The problem is how to actually print.
Technically qDebug() << str; works fine for unicode; however qDebug, qWarning, etc. are overwritten by installing a different message handler.

The question is very simple:

QString s = "őű";
    // ????: printf("%s\n", s);
    // ????: printf("%s\n", s.toAscii());
    // ????: etc.
    // What to put there instead of printf?

QString s = "őű";
    // ????: printf("%s\n", s);
    // ????: printf("%s\n", s.toAscii());
    // ????: etc.
    // What to put there instead of printf?

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console used: konsole

[wysota]

Please answer my question --- what encoding does your console use. If it's utf-8 then qDebug() << str.toUtf8() should work. If it's something else then probably str.to8BitEncoding() will work.

[sandor]

I tried both of those down below. Any idea would help.

static QTextCodec *pCodec = QTextCodec::codecForName("UTF-8");
 
    // pCodec is available through the application; does not go out of scope, not that it would even matter
 
    if (pCodec == 0) {
        qCritical("UTF-8 is not supported by the O/S or shell");
        return;
    }
 
    QTextCodec::setCodecForCStrings(pCodec);
    QTextCodec::setCodecForLocale(pCodec);
    QTextCodec::setCodecForTr(pCodec);
 
    // Print here with anything else but qDebug, qWarning, qCritical and qFatal

static QTextCodec *pCodec = QTextCodec::codecForName("UTF-8");

    // pCodec is available through the application; does not go out of scope, not that it would even matter

    if (pCodec == 0) {
        qCritical("UTF-8 is not supported by the O/S or shell");
        return;
    }

    QTextCodec::setCodecForCStrings(pCodec);
    QTextCodec::setCodecForLocale(pCodec);
    QTextCodec::setCodecForTr(pCodec);

    // Print here with anything else but qDebug, qWarning, qCritical and qFatal

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The default encoding of Konsole on CentOS is UTF-8; and that is used.

---

Added after 28 minutes:

Actually, solved. I think build was not cleaned properly.

[ChrisW67]

Well, hmm, it does not quite work. Actually the problem is not how to put into QString, it is the easy part.

I don't think you understand the problem.

The problem is how to actually print.
The question is very simple:

QString s = "őű";
    // ????: printf("%s\n", s);
    // ????: printf("%s\n", s.toAscii());
    // ????: etc.
    // What to put there instead of printf?

QString s = "őű";
    // ????: printf("%s\n", s);
    // ????: printf("%s\n", s.toAscii());
    // ????: etc.
    // What to put there instead of printf?

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Well, printf() will work, and so will std::cout, QTextStream and qDebug but you'll will only see the characters you expect if they get into the QString correctly in the first place.

#include <QtCore>
#include <QDebug>
#include <iostream>
 
void output(const QString &s) {
    printf("%s\n", s.toUtf8().data());
    std::cout << s.toUtf8().data() << std::endl;
    QTextStream out(stdout);
    out << s << endl;
    qDebug() << s;
    qDebug() << "-----";
}
 
 
int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
 
    QString s("áéőűÁÉŐŰ");  // mangled by toAscii()
    output(s);
    s = "áéőűÁÉŐŰ";  // mangled by toAscii() too
    output(s);
    s = QString::fromUtf8("áéőűÁÉŐŰ"); // not mangled
    output(s);
 
    return 0;
}

#include <QtCore>
#include <QDebug>
#include <iostream>

void output(const QString &s) {
    printf("%s\n", s.toUtf8().data());
    std::cout << s.toUtf8().data() << std::endl;
    QTextStream out(stdout);
    out << s << endl;
    qDebug() << s;
    qDebug() << "-----";
}


int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    QString s("áéőűÁÉŐŰ");  // mangled by toAscii()
    output(s);
    s = "áéőűÁÉŐŰ";  // mangled by toAscii() too
    output(s);
    s = QString::fromUtf8("áéőűÁÉŐŰ"); // not mangled
    output(s);

    return 0;
}

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Just for reference I am using Konsole with UTF8 encoding and suitable fonts. This is the output:

áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
"áéÅűÃÃÅÅ°" 
----- 
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
"áéÅűÃÃÅÅ°" 
----- 
áéőűÁÉŐŰ
áéőűÁÉŐŰ
áéőűÁÉŐŰ
"áéőűÁÉŐŰ" 
-----

áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
"áéÅűÃÃÅÅ°" 
----- 
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
áéÅűÃÃÅÅ°
"áéÅűÃÃÅÅ°" 
----- 
áéőűÁÉŐŰ
áéőűÁÉŐŰ
áéőűÁÉŐŰ
"áéőűÁÉŐŰ" 
-----

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