hexadecimal to decimal conversion

[reshu]

Hi
I am trying to convert a 32 bit hexadecimal number located at 4 consecutive locations in a QByte array to decimal number. but i am not getting the correct value.```
QByteArray D1;
D1.resize(4);
D1[0]=0xAB; //MSB
D1[1]=0xCD;
D1[2]=0xEF;
D1[3]=0x00; //LSB

//// option 1
encoder_sp_temp = qFromBigEndian<qint32>(D1.mid(0, 4).toHex());
ui->encoder_sp->setText(QByteArray::number(encoder_sp_temp));
ui->encoder_sp->setText(QByteArray::number(encoder_sp_temp,10));
Answer i am getting is 1633837924 instead of 288240000

//// option 2
ui->encoder_sp->setText(QByteArray().append(D1[0]).append(D1[1]).append(D1[2]).append(D1[3]).toHex());
hex value displayed correctly

///option 3
qint32 value=D1.at(0)<<24|D1.at(1)<<16|D1.at(2)<<8|D1.at(0);
ui->encoder_sp->setText(QString::number(value,10));

please help to resolve this issue
Reshu

[Bonnie]

Why are you using toHex()????That will convert the number to hex string!!! A string!!! Not number!!! Just

encoder_sp_temp = qFromBigEndian<quint32>(D1.constData());

Do note that encoder_sp_temp should be a quint32 instead of qint32, or you'll get a negative number.

Since I've answered your several questions, I think you really need to understand toHex() and QByteArray...
The result of toHex() is a string, you can't use it as a number anymore.

[J.Hilk]

@reshu
first of, a uint32 is a uint32 there is no hexadecimal number or decimal number inside a QByteArry everything is a char.

A hexadecimal number is just a visual representation
in your case here a simple

QByteArray D1;
    D1.resize(4);
    D1[0]=0xAB; //MSB
    D1[1]=0xCD;
    D1[2]=0xEF;
    D1[3]=0x00; //LSB


    quint32 value = qFromBigEndian<quint32>(D1);
    qDebug() << value << QString::number(value, 10) << QString::number(value, 16);

will do just fine.
But since you're doing mid() calls, I suggest a QDataStream instead:

QByteArray D1;
    D1.resize(4);
    D1[0]=0xAB; //MSB
    D1[1]=0xCD;
    D1[2]=0xEF;
    D1[3]=0x00; //LSB
    //Junk data
    D1[4]= 0xFF;
    D1[5]= 0xFF;
    D1[6]= 0xFF;
    D1[7]= 0xFF;
    //other number
    D1[8]=0xAB; //MSB
    D1[9]=0xCD;
    D1[10]=0xEF;
    D1[11]=0x00; //LSB


    QDataStream out(D1);
    out.setByteOrder(QDataStream::BigEndian);

    quint32 value1;
    out >> value1;
    out.skipRawData(4);

    quint32 value2;
    out >> value2;
    qDebug() << value1 << QString::number(value1, 10) << QString::number(value1, 16);
    qDebug() << value2 << QString::number(value2, 10) << QString::number(value2, 16);

[reshu]

@Bonnie thanks. got correct when changed to quint32. actually the data is that of an encoder which gives both positive and negative values depending on direction of rotation.
Reshu