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Thread: Convert QbyteArray to int return 0 (problem)

  1. #1
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    Default Convert QbyteArray to int return 0 (problem)

    Hello,

    I convert a QByteArray to int using the toInt() function
    So when I try to display the int value, its return 0
    I'm trying also toUInt()

    Qt Code:
    1. QByteArray* ByteID = new QByteArray;
    2. ByteID = oneFrame.mid(3,1);
    3. qDebug() << "ByteID = " << (*ByteID).toHex(); // return 0A --> working perfectly
    4. qDebug() << "ByteID = " << (*ByteID).toUInt(); // return 0
    To copy to clipboard, switch view to plain text mode 

    I'm serching on Google but I don't find a correct response

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Better read documentation than google
    Qt Code:
    1. // example from QByteArray::toInt docs:
    2. QByteArray str("FF");
    3. bool ok;
    4. int hex = str.toInt(&ok, 16); // hex == 255, ok == true
    5. int dec = str.toInt(&ok, 10); // dec == 0, ok == false
    To copy to clipboard, switch view to plain text mode 

  3. The following user says thank you to stampede for this useful post:

    AUDI_ENG (8th July 2014)

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Quote Originally Posted by stampede View Post
    Better read documentation than google
    Qt Code:
    1. // example from QByteArray::toInt docs:
    2. QByteArray str("FF");
    3. bool ok;
    4. int hex = str.toInt(&ok, 16); // hex == 255, ok == true
    5. int dec = str.toInt(&ok, 10); // dec == 0, ok == false
    To copy to clipboard, switch view to plain text mode 
    I readed documentation , I'm trying this code, nothing changed, I have 0 as result (for dec)


    nb data read = 11 Data readed = "aaaa0c0e09090a0809090a"
    Qt Code:
    1. *ByteID = oneFrame.mid(2,1);
    2. int dec = (*ByteID).toInt(&ok,16);
    To copy to clipboard, switch view to plain text mode 
    ByteID_hex = "0c"
    dec = 0
    Last edited by AUDI_ENG; 8th July 2014 at 10:38.

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Hi,

    "FF" is not a valid value in decimal representation but is a valid value in hexadecimal. This is what "ok" variable is telling you.
    Òscar Llarch i Galán

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    AUDI_ENG (8th July 2014)

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Quote Originally Posted by ^NyAw^ View Post
    Hi,

    "FF" is not a valid value in decimal representation but is a valid value in hexadecimal. This is what "ok" variable is telling you.
    Hi,
    Ok thank you, So How I can convert the QbyteArray to a valid decimal value ?

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    Default Re: Convert QbyteArray to int return 0 (problem)

    But QByteArray::toInt works with "string equivalent of the number". 0x0C is NOT valid ASCII digit.

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    AUDI_ENG (8th July 2014)

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Thank you for this clear response
    So, Qt has another function to convert a QByteArray to Int?
    Last edited by AUDI_ENG; 8th July 2014 at 12:11.

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    Default Re: Convert QbyteArray to int return 0 (problem)

    In example look at this thread

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    AUDI_ENG (8th July 2014)

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Quote Originally Posted by Lesiok View Post
    In example look at this thread
    Thank you So MUCH Lesiok

    it's working :

    Qt Code:
    1. int dec = static_cast<quint8>(oneFrame.at(2)); //example : 2 is the 3th byte in oneframe
    To copy to clipboard, switch view to plain text mode 

  14. #10
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    Default Re: Convert QbyteArray to int return 0 (problem)

    You should write like this :
    Qt Code:
    1. int dec = static_cast<int>(oneFrame.at(2)); //example : 2 is the 3th byte in oneframe
    To copy to clipboard, switch view to plain text mode 
    Why do two conversions ?

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Quote Originally Posted by Lesiok View Post
    You should write like this :
    Qt Code:
    1. int dec = static_cast<int>(oneFrame.at(2)); //example : 2 is the 3th byte in oneframe
    To copy to clipboard, switch view to plain text mode 
    Why do two conversions ?
    I don't know, can you explain me ? (where are the two convertions) ?

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    Default Re: Convert QbyteArray to int return 0 (problem)

    In Yours code :
    1. First explicit conversion static_cast<quint8>
    2. Second implicit conversion (by compiler) from quint8 to int (type of variable).

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    Default Re: Convert QbyteArray to int return 0 (problem)

    Quote Originally Posted by Lesiok View Post
    In Yours code :
    1. First explicit conversion static_cast<quint8>
    2. Second implicit conversion (by compiler) from quint8 to int (type of variable).
    OK Thank you

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