Why can't I parse a XML file using QXmlStreamReader from Qt?

Question

I'm trying to figure out how QXmlStreamReader works for a C++ application I'm writing. The XML file I want to parse is a large dictionary with a convoluted structure and plenty of Unicode characters so I decided to try a small test case with a simpler document. Unfortunately, I hit a wall. Here's the example xml file:

<?xml version="1.0" encoding="UTF-8" ?>
<persons>
    <person>
        <firstname>John</firstname>
        <surname>Doe</surname>
        <email>[email protected]</email>
        <website>http://en.wikipedia.org/wiki/John_Doe</website>
    </person>
    <person>
        <firstname>Jane</firstname>
        <surname>Doe</surname>
        <email>[email protected]</email>
        <website>http://en.wikipedia.org/wiki/John_Doe</website>
    </person>
    <person>
        <firstname>Matti</firstname>
        <surname>Meikäläinen</surname>
        <email>[email protected]</email>
        <website>http://fi.wikipedia.org/wiki/Matti_Meikäläinen</website>
    </person>
</persons>

...and I'm trying to parse it using this code:

int main(int argc, char *argv[])
{
    if (argc != 2) return 1;

    QString filename(argv[1]);
    QTextStream cout(stdout);
    cout << "Starting... filename: " << filename << endl;

    QFile file(filename);
    bool open = file.open(QIODevice::ReadOnly | QIODevice::Text);
    if (!open) 
    {
        cout << "Couldn't open file" << endl;
        return 1;
    }
    else 
    {
        cout << "File opened OK" << endl;
    }

    QXmlStreamReader xml(&file);
    cout << "Encoding: " << xml.documentEncoding().toString() << endl;

    while (!xml.atEnd() && !xml.hasError()) 
    {
        xml.readNext();
        if (xml.isStartElement())
        {
            cout << "element name: '" << xml.name().toString() << "'" 
                << ", text: '" << xml.text().toString() << "'" << endl;
        }
        else if (xml.hasError())
        {
            cout << "XML error: " << xml.errorString() << endl;
        }
        else if (xml.atEnd())
        {
            cout << "Reached end, done" << endl;
        }
    }

    return 0;
}

...then I get this output:

C:\xmltest\Debug>xmltest.exe example.xml
Starting... filename: example.xml
File opened OK
Encoding:
XML error: Encountered incorrectly encoded content.

What happened? This file couldn't be simpler and it looks consistent to me. With my original file I also get a blank entry for the encoding, the entries' names() are displayed, but alas, the text() is also empty. Any suggestions greatly appreciated, personally I'm thorougly mystified.

Answer 1

I'm answering this myself as this problem was related to three issues, two of which were brought up by the responses.

1. The file actually wasn't UTF-8 encoded. I changed the encoding to iso-8859-1 and the encoding warning disappeared.
2. The text() function doesn't work as I expected. I have to use readElementText() to read the entries' contents.
3. When I try to readElementText() on an element that doesn't contain text, like the top-level <persons> in my case, the parser returns an "Expected character data" error and the parsing is interrupted. I find this behaviour strange (in my opinion returning an empty string and continuing would be better) but I guess as long as the specification is known, I can work around it and avoid calling this function on every entry.

The relevant code section that works as expected now looks like this:

while (!xml.atEnd() && !xml.hasError()) 
{
    xml.readNext();
    if (xml.isStartElement())
    {
        QString name = xml.name().toString();
        if (name == "firstname" || name == "surname" || 
            name == "email" || name == "website")
        {
            cout << "element name: '" << name  << "'" 
                         << ", text: '" << xml.readElementText() 
                         << "'" << endl;
        }
    }
}
if (xml.hasError())
{
    cout << "XML error: " << xml.errorString() << endl;
}
else if (xml.atEnd())
{
    cout << "Reached end, done" << endl;
}

Answer 2

The file is not UTF-8 encoded. Change the encoding to iso-8859-1 and it will parse without error.

<?xml version="1.0" encoding="iso-8859-1" ?>