Can somebody show how to read bytes?

["BumbleBee"]

Hey people,I've been searching for hours now about how to read bytes from a file.
What I want to do,is open an .exe file,take the bytes and output them as binary(100101)/hex(FFA2)...

I have searched this in plain c++ and Qt as well..but none good answer.
All I get are some strange chars,or a string "MZP" in console....

I have tried QFile,QIODevice,QByteArray..but no result.

Can anyone please explain me how to do this?

Thanks.

[high_flyer]

I have tried QFile,QIODevice,QByteArray..but no result.

Show what you have tried.

[wysota]

Hey people,I've been searching for hours now about how to read bytes from a file.

QIODevice::read()

All I get are some strange chars,or a string "MZP" in console....

And what did you expect to receive? A happy smiling face?

["BumbleBee"]

Well,I have tried many different combination with different syntax...I cannot post a certain code,as there were many things I tried..

Can you please post a working piece?

[high_flyer]

Post the the code you thought was the best of the things you tried, and we can pick it up from there.

["BumbleBee"]

Sure.
Well I made this:

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QDebug>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QFile f("C:\\Program Files (x86)\\TeamViewer\\Version6\\TeamViewer.exe");
        if( !f.exists() )
 
             {
              // It does not exist
               qDebug() << "The file does not exist.\n";
             }
 
            // It exists, open it
             if(!f.open(QIODevice::ReadOnly))
             {
              // It could not open
               qDebug() << "Failed to open.";
 
               return 0;
             }
 
            // It opened, now we need to close it
             qDebug() << "Success";
 
             int size = f.size();
             qDebug() << "size: " << size;
 
            QDataStream data(&f);
            char * buffer;
            uint u = sizeof(f);
            data.readBytes(buffer,u);
 
 
             f.close();
             return a.exec();
}

#include <QtCore/QCoreApplication>
#include <QFile>
#include <QDebug>

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

    QFile f("C:\\Program Files (x86)\\TeamViewer\\Version6\\TeamViewer.exe");
        if( !f.exists() )

             {
              // It does not exist
               qDebug() << "The file does not exist.\n";
             }

            // It exists, open it
             if(!f.open(QIODevice::ReadOnly))
             {
              // It could not open
               qDebug() << "Failed to open.";

               return 0;
             }

            // It opened, now we need to close it
             qDebug() << "Success";

             int size = f.size();
             qDebug() << "size: " << size;

            QDataStream data(&f);
            char * buffer;
            uint u = sizeof(f);
            data.readBytes(buffer,u);


             f.close();
             return a.exec();
}

To copy to clipboard, switch view to plain text mode 

Then I thought that I may need to make a loop,in order to read a byte after byte..but still nothing.

[wysota]

The code doesn't make much sense really. Why don't you just use QIODevice::read() on your QFile object?

[mcosta]

Sorry,

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
    QFile f("C:\\Program Files (x86)\\TeamViewer\\Version6\\TeamViewer.exe");
 
....
             int size = f.size();
             qDebug() << "size: " << size;
 
            QDataStream data(&f);
            char * buffer;
            uint u = sizeof(f);
            data.readBytes(buffer,u);
 
 
             f.close();
             return a.exec();
}

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

    QFile f("C:\\Program Files (x86)\\TeamViewer\\Version6\\TeamViewer.exe");

....
             int size = f.size();
             qDebug() << "size: " << size;

            QDataStream data(&f);
            char * buffer;
            uint u = sizeof(f);
            data.readBytes(buffer,u);


             f.close();
             return a.exec();
}

To copy to clipboard, switch view to plain text mode 

what you're doing??

1. You're using a pointer "buffer" as array of bytes (WRONG)
2. You're using sizeof of an object as amount of data to read (WRONG)

for 1. it's strange that your program doesn't crash

I suggest you

int size = f.size();
    qDebug() << "size: " << size;
 
    QByteArray buffer = f.read (size);

int size = f.size();
    qDebug() << "size: " << size;

    QByteArray buffer = f.read (size);

To copy to clipboard, switch view to plain text mode 

and use directly "buffer"

[squidge]

All I get are some strange chars,or a string "MZP" in console....

Which is the ascii representation of the file [All EXE files start with the letters 'MZ'], so you have already managed to read the file. All you need to do is convert your ascii into hex or binary. See the docs on how to do that or write your own conversion function.

[ChrisW67]

You do not need or want to use QDataStream for this task. As Wysota points out a simple call to QIODevice::read() or readAll() will suffice. As mcosta points out you are flirting with crashing by using a char* pointer that is not initialised to point at allocated memory: Qt provides structures to handle this for you.

Your problem comes down to:

1. Open file and report error if file not opened: See QFile and QIODevice open() and errorString().
2. Read file content into memory. See QByteArray and QIODevice::read() or readAll().
3. Close file. See QFile::close()
4. Do something with content. See QByteArray::toHex()

That description is about the same length as a basic implementation.

[wysota]

To suplement what was already said - I strongely discourage you from reading the whole file into memory since 1) you don't know how big it is and 2) most likely you don't need to have all the data available at once. Read as much as you need, process it and then read more if you need more.

["BumbleBee"]

int size = f.size();
 
             QByteArray bytes = f.readAll();
 
             qDebug() << bytes; //outputs ""MZP
 
             qDebug() << bytes.toHex(); //Same output :(

int size = f.size();

             QByteArray bytes = f.readAll();
            
             qDebug() << bytes; //outputs ""MZP

             qDebug() << bytes.toHex(); //Same output :(

To copy to clipboard, switch view to plain text mode 

[mcosta]

What do you expect to read??

You're reading a binary file!

["BumbleBee"]

What do you mean?

I want to convert that to hex...

[mcosta]

For me this code

char data [] = { 0xaa, 0x01, 0x00, 0xFF, 0xBA};
    QByteArray ba (data, 5);
 
    qDebug() << ba;
    qDebug() << ba.toHex();

char data [] = { 0xaa, 0x01, 0x00, 0xFF, 0xBA};
    QByteArray ba (data, 5);

    qDebug() << ba;
    qDebug() << ba.toHex();

To copy to clipboard, switch view to plain text mode 

print

"ª

"aa0100ffba"

"ª

"aa0100ffba"

To copy to clipboard, switch view to plain text mode 

["BumbleBee"]

How is this related to my source?
i get MZP when reading Anscii like wysota said.
But Chris said I have to convert that QBA to hex..which doesn't work...

[wysota]

But Chris said I have to convert that QBA to hex..which doesn't work...

What doesn't work? What's the point of dumping the whole file to the screen in its hexadecimal form?

#include <QFile>
#include <stdio.h>
 
int main(int argc, char **argv) {
  QFile f(argv[1]);
  f.open(QFile::ReadOnly);
  int offset = 0;
  while(!f.atEnd()){
      QByteArray ba = f.read(16).toHex();
      QString offsetStr = QString::number(offset, 16);
      while(offsetStr.size()<8) offsetStr.prepend('0');
      printf("0x%s\t", qPrintable(offsetStr));
      offset+=16;
 
      for(int i=ba.size()-2;i>0;i-=2) {
	ba.insert(i, ' ');
      }
 
      printf("%s\n", ba.constData());
  }
  return 0;
}

#include <QFile>
#include <stdio.h>

int main(int argc, char **argv) {
  QFile f(argv[1]);
  f.open(QFile::ReadOnly);
  int offset = 0;
  while(!f.atEnd()){
      QByteArray ba = f.read(16).toHex();
      QString offsetStr = QString::number(offset, 16);
      while(offsetStr.size()<8) offsetStr.prepend('0');
      printf("0x%s\t", qPrintable(offsetStr));
      offset+=16;
      
      for(int i=ba.size()-2;i>0;i-=2) {
	ba.insert(i, ' ');
      }
      
      printf("%s\n", ba.constData());
  }
  return 0;
}

To copy to clipboard, switch view to plain text mode 

[mcosta]

Why doesn't work?

This code

void Widget::on_openFileButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName (
                this,
                tr ("Open File"),
                ".",
                tr ("Executable files (*exe)"));
 
    if (!fileName.isEmpty ()) {
        QFile f (fileName);
 
        const int SIZE = 100;
        int readSize;
 
        f.open (QIODevice::ReadOnly);
        readSize = (f.size () > SIZE)? SIZE: f.size ();
 
        QByteArray ba = f.read (readSize);
 
        ui->rawDataEdit->setPlainText (ba);
        ui->hexDataEdit->setPlainText (ba.toHex ());
    }
}

void Widget::on_openFileButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName (
                this,
                tr ("Open File"),
                ".",
                tr ("Executable files (*exe)"));

    if (!fileName.isEmpty ()) {
        QFile f (fileName);

        const int SIZE = 100;
        int readSize;

        f.open (QIODevice::ReadOnly);
        readSize = (f.size () > SIZE)? SIZE: f.size ();

        QByteArray ba = f.read (readSize);

        ui->rawDataEdit->setPlainText (ba);
        ui->hexDataEdit->setPlainText (ba.toHex ());
    }
}

To copy to clipboard, switch view to plain text mode 

shows this output when I select a EXE file

imagine1.JPG

[ChrisW67]

int size = f.size();
 
             QByteArray bytes = f.readAll();
 
             qDebug() << bytes; //outputs ""MZP
 
             qDebug() << bytes.toHex(); //Same output :(

int size = f.size();

             QByteArray bytes = f.readAll();
            
             qDebug() << bytes; //outputs ""MZP

             qDebug() << bytes.toHex(); //Same output :(

To copy to clipboard, switch view to plain text mode 

Unpossible!

["BumbleBee"]

What doesn't work? What's the point of dumping the whole file to the screen in its hexadecimal form?

#include <QFile>
#include <stdio.h>
 
int main(int argc, char **argv) {
  QFile f(argv[1]);
  f.open(QFile::ReadOnly);
  int offset = 0;
  while(!f.atEnd()){
      QByteArray ba = f.read(16).toHex();
      QString offsetStr = QString::number(offset, 16);
      while(offsetStr.size()<8) offsetStr.prepend('0');
      printf("0x%s\t", qPrintable(offsetStr));
      offset+=16;
 
      for(int i=ba.size()-2;i>0;i-=2) {
	ba.insert(i, ' ');
      }
 
      printf("%s\n", ba.constData());
  }
  return 0;
}

#include <QFile>
#include <stdio.h>

int main(int argc, char **argv) {
  QFile f(argv[1]);
  f.open(QFile::ReadOnly);
  int offset = 0;
  while(!f.atEnd()){
      QByteArray ba = f.read(16).toHex();
      QString offsetStr = QString::number(offset, 16);
      while(offsetStr.size()<8) offsetStr.prepend('0');
      printf("0x%s\t", qPrintable(offsetStr));
      offset+=16;
      
      for(int i=ba.size()-2;i>0;i-=2) {
	ba.insert(i, ' ');
      }
      
      printf("%s\n", ba.constData());
  }
  return 0;
}

To copy to clipboard, switch view to plain text mode 

I need to take the hex,in order to encrypt it and save it as a new exe...btw,your code makes an infinite loop....