How to make QFile read the whole line

[JohanSolo]

How are you determining QFile is stopping at the char( 0 )? If you're using a (const) char[], a std::string or QString any character after 0 won't be displayed even if set, as 0 is the string terminator. Are you sure the data is not loaded or could it be is is simply not displayed?

[ManiRon]

@VRonin

   file.read(checksum,32); // Actually first 32 byte are checksum and the remaining are data
    qDebug("Data %s",checksum);
    file.seek(33);
    size_of_file = file.size() - 33;
    qDebug("FILESIZE %d",size_of_file);
        fileData = file.read(size_of_file);
        qDebug("FILEDATA %s",fileData.data());
    qDebug("FILEDATA1 %s",fileData.data());
    FileHashData= QCryptographicHash::hash(fileData, QCryptographicHash::Md5);
    qDebug() << FileHashData.toHex();

[VRonin]

All the types are missing there. What type is fileData? ho do you open file ?

[JonB]

@ManiRon said in How to make QFile read the whole line:

   file.read(checksum,32); // Actually first 32 byte are checksum and the remaining are data
    qDebug("Data %s",checksum);
    file.seek(33);
    size_of_file = file.size() - 33;

If your checksum is 32 bytes it occupies bytes #0 to #31 inclusive (like an array). You then seek to 33. Just to verify, that means you are "skipping" 1 byte at offset 32 in the file. Is that really what you intend?

[ManiRon]

@JonB

its a single line data i have taken sreenshot like this . After the data 61 the next starts as d2.

As per the above image the file read reads till A.,?E>t1?dWQA.,DE_??n1?d7be1526df618c0c4d1bab3959adb65ada9f20bd969493e532a7861d29bc6e698

[JonB]

@ManiRon
I have no idea how that answers my question. Only you know how byte #32 is or is not used in the file. It's up to you.

Meanwhile, you should be answering @VRonin's

All the types are missing there. What type is fileData? ho do you open file ?

[ManiRon]

@VRonin int cRetVal = 0;

  int cRetVal = 0;
QByteArray FileHashData, fileData;
char checksum[32];
qint64 size_of_file;

strUserName = ui->le_Username->text();
m_usrname = ui->le_Username->text();


char carrUsrPwdHash[65] = {"\0"};
QString UsrPwdHash;

QFile file("userpass");

if (file.open(QIODevice::ReadOnly))
{
    file.read(checksum,32);
    qDebug() << checksum;
    file.seek(33);
    size_of_file = file.size() - 33;
    fileData = file.read(size_of_file);

    qDebug("FILEDATA %s",fileData.data());
    FileHashData= QCryptographicHash::hash(fileData, QCryptographicHash::Md5);
    qDebug() << FileHashData.toHex();
}

[ManiRon]

@ManiRon
in that image b5afa24a9fa264a178f5ae63c7eff6cf this is my checksum after that a Nul character is there after which my actual data starts

[JonB]

@ManiRon
OK, in that case it sounds right if it is followed by a "Nul". Personally I would put a comment into your code then to explain that is why you are seeking to byte #33.

I don't see anything which would stop at a NUL in your code. What makes you think it is doing so? Are you just relying on the output of qDebug("FILEDATA %s",fileData.data()); and thinking that shows it has not read past a NUL, that may be an artefact of how qDebug() displays the data? Try debugging out the length of the data?

[ManiRon]

@JonB Actually my requirement is to calculate checksum for the data and store it in the same file where the data i am writing to . So i planned to write the checksum at the begining and followed by the data.

Now when i start the application i will validate the file by reading the checksum stored in file and compare it with the remaining data in file by calculating checksum for them .

Note the stored checksum is calculated using the data and not the whole file

[VRonin]

could you replace fileData = file.read(size_of_file); with :

fileData.resize(size_of_file);
const auto actualRead = file.read(fileData.data(),size_of_file);
Q_ASSERT(actualRead==size_of_file);

[ManiRon]

@VRonin said in How to make QFile read the whole line:

actualRead

I tried sir but i am getting this kind of error

[jsulm]

@ManiRon It's not hard to fix:

const qint64 actualRead = file.read(fileData.data(),size_of_file);

[ManiRon]

@jsulm said in How to make QFile read the whole line:

const qint64 actualRead

error resolved

[ManiRon]

@VRonin but thsi doest read the full data

[ManiRon]

@JonB

No sir i checked the read by removing the NUL from the data in the file and i was able to see that it read the whole data and qDebug() was displaying the full data

This is the whole data when i removed the NUL : " WQA.,?E>t1?dWQA.,DE_??n1?d7be1526df618c0c4d1bab3959adb65ada9f20bd969493e532a7861d29bc6e698{TB.)?V1??n1?dS[H21?z7_??n1?d340819615bcd7cb87459cac37070456eb0af53716c1f0064c4771857728d3777 "

[ManiRon]

@ManiRon

But when the data conatins NUL the data will be " WQA.,?E>t1?dWQA.,DE_??n1?d7be1526df618c0c4d1bab3959adb65ada9f20bd969493e532a7861d29bc6e698 "

[jsulm]

@ManiRon said in How to make QFile read the whole line:

but thsi doest read the full data

What is the output of

qDebug() << actualRead << size_of_file;

?

[ManiRon]

@jsulm said in How to make QFile read the whole line:

size_of_file

Size = 194 .

I thought it was qdebug problem so i wrote the data read from the file to another file then also it remains the same as the data shown in the debug

[VRonin]

What is the value of actualRead?