Problem with QStream adding Extra Characters After a flush?

[ndt_mike]

I have a work around but do not understand why I am experiencing this problem.

I am using QT 5.6 on Ubuntu (not sure what version).

I have the following code:

    #include <QCoreApplication>
    #include <QDebug>
    #include <QFile>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    bool ok = false, second = false;
    double dr = 0.0;
    double dm = 0.0;
    QString tofile;
    QTextStream debug(&tofile);
    QString line = "the cow jumped over the moon 100.0 -1.0 foo bar";
    QString buffer;
    QTextStream bufferstream(& buffer);
    QStringList list = line.split(" ");

    foreach(buffer, list){
        debug<< "buffer before stream: " << buffer << '\n';
        buffer.toDouble( &ok );
        if(ok == true && second == true ){//found second valid double
            bufferstream >> dm;
            debug<< "buffer after stream and flush: "<< buffer << '\n';
            break;
        }
        if(ok == true && second == false){//found the first valid double
            second = true;
            bufferstream >> dr;
            debug<< "buffer first stream: " << buffer << '\n';
            bufferstream.flush();
        }
    }

    debug<< "dm: "<< dm << "dr: "<< dr;

    qDebug()<< tofile;

    QFile file("StreamTestFile.txt");
    if (!file.open(QFile::WriteOnly | QFile::Text)) {
        qDebug()<<"error!";
    }

    QTextStream out(&file);
    out << tofile;
    file.close();

    return a.exec();
}

After the second stream to extract the second double it adds characters, here is the output

buffer before stream: the
buffer before stream: cow
buffer before stream: jumped
buffer before stream: over
buffer before stream: the
buffer before stream: moon
buffer before stream: 100.0
buffer first stream: 100.0
buffer before stream: -1.0
buffer after stream and flush: -1.\00
dm: 0dr: 100

so you do not get the correct double. Any explanation? I fixed it by making new QTextStreams in each if statement...

just tried this in Windows (minGW) and got the same thing.

[kshegunov]

You're doing it wrong. Just use the stream to read from the string:

QString line = "the cow jumped over the moon 100.0 -1.0 foo bar", word;
QTextStream in(&line);
while (!in.atEnd())  {
    in >> word;

    bool ok;
    double value = word.toDouble(&ok);
    if (!ok)
        continue;
     // ...
}

[ndt_mike]

@kshegunov

Yeah thanks I am aware of that method.

Frankly have been reading a bit and 'discovered' the stream method to convert from QString to double and thought, 'Oh Cool let's do this!!" .

Then I ran into the problem shown above. I guess I am one of the few people crazy enough to try it.

Still appreciate the feedback thanks.