QBitArray to QByteArray

Question

When we create a text file with this text "ali ata bak", and we use this file as input for the program. The code is running normally. But when we enter "1111111111111111111111" this text in the textfile, Code isnt running expected. So What is the problem?

#include <QtCore/QCoreApplication>
#include <QBitArray>
#include <QByteRef>
#include <QFile>
#include <iostream>
#include <stdlib.h>
#include <QTextStream>

// Buffer Size #num of KB's
#define BUFFER_SIZE_KB 1

// Do not change !!
#define BUFFER_SIZE_BYTE BUFFER_SIZE_KB*1024
#define BUFFER_SIZE_BIT  BUFFER_SIZE_BYTE*8

using namespace std;


QBitArray bytesToBits(QByteArray bytes) {
    QBitArray bits(bytes.count()*8);
    // Convert from QByteArray to QBitArray
    for(int i=0; i<bytes.count(); ++i)
        for(int b=0; b<8; ++b)
            bits.setBit(i*8+b, bytes.at(i)&(1<<b));
    return bits;
}


QByteArray bitsToBytes(QBitArray bits) {
    QByteArray bytes;
    bytes.resize(bits.count()/8);
    // Convert from QBitArray to QByteArray
    for(int b=0; b<bits.count(); ++b)
        bytes[b/8] = ( bytes.at(b/8) | ((bits[b]?1:0)<<(b%8)));
    return bytes;
}


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QString inFilename;
    QString outFilename;
    QTextStream qtin(stdin);


    cout << "Filename : ";
    qtin >> inFilename;
    outFilename.append("_");
    outFilename.append(inFilename);

    QFile infile(inFilename);
    if (!infile.open(QIODevice::ReadOnly)) {
        cout << "\nFile cant opened\n";
        system("pause");
        return 1;
    }

    QFile outfile(outFilename);
    if (!outfile.open(QIODevice::WriteOnly)) {
        cout << "\nFile cant opened\n";
        system("pause");
        return 2;
    }

    QByteArray bytes, bytes2;
    QBitArray bits;


    while ((bytes = infile.read(BUFFER_SIZE_BYTE)) >0 ) {

        bits = bytesToBits(bytes);
        bytes2 = bitsToBytes(bits);// PROBLEM IS HERE
        outfile.write(bytes2);

    }

    outfile.close();
    infile.close();
    cout << "Finished\n";
    return a.exec();
}

Answer 1

Initialization problem.

QByteArray bitsToBytes(QBitArray bits) {
    QByteArray bytes;
    bytes.resize(bits.count()/8+1);
    bytes.fill(0);
    // Convert from QBitArray to QByteArray
    for(int b=0; b<bits.count(); ++b)
        bytes[b/8] = ( bytes.at(b/8) | ((bits[b]?1:0)<<(b%8)));
    return bytes;
}

this produces the right answer

Answer 2

QByteArray bitsToBytes(const QBitArray& bits)
{
    QByteArray bytes;
    QDataStream stream(&bytes, QIODevice::WriteOnly);
    stream << bits;
    return bytes;
}

Answer 3

You might also want to read about endianness from the Wikipedia http://en.wikipedia.org/wiki/Endianness