Thread: C++ / Qt5.8 - Read file into char vector

Hello,

I'm reading a USB stick into an unsigned char vector.
Not a problem, Method 1 is obviously faster than Method 2.
As you can see I'm reading into a buffer and then putting the data into the vector.
In Method 1, would it be possible to read straight into the vector? If so, how?

Regards

Code:

    std::vector <unsigned char> buff;
    buff.reserve(size);

Code:

Method 1
    //check on file size
    unsigned char data[512];
    infile.read((char *)&data, size);
    for (int i = 0; i < size; i++)
    {
        buff.push_back(data[i]);
        printf("%i - %c, ", i, data);
    }

Code:

Method 2
    unsigned char data[1];
    for (int i = 0; i < size; i++)
    {
        if (infile.eof()) // check for EOF
        {
            printf("EOF reached\n");
            cin.get();
            exit (999);
        }

        infile.read((char *)&data, sizeof(data));
        buff.push_back(data);
        printf("%i - %c, ", i, data);
    }

Hello,

Thanks for the code.

Originally Posted by algorism

Code:

// C++11
buff.resize(size);
infile.read((char *)buff.data(), size);

And you're not checking for eof properly in Method 2. Think about it.

And you are still using printf in C++.

Is this better?

Code:

    if ( (infile.read((char *)buff.data(), size)).eof() )
    {
        std::cout << "EOF reached!" << endl;
        std::cin.get();
        return (105);
    }

The printf's are only for testing, I'm used to them.

c99tutorial My mistake.

Regards

For eof testing in your "Method 2", I was thinking something like this:

Code:

    char data;
    for (int i = 0; i < size; i++)
    {
        if (!infile.read(&data, 1))  // or if(!infile.get(&data))
        {
            cout << "EOF reached\n";
            cin.get();
            exit(99);
        }
        buff.push_back((unsigned char)data);
        cout << i << " - " << data << ", ";
    }