Why do the two reading code blocks produce different output?

ostream-istream.cc

#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
#include <vector>

int main(int argc, const char *argv[]) {

    {
        std::ofstream outfile;
        outfile.open("test", std::ios::binary);

        unsigned char a[] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 
            0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
        unsigned char *begin = &a[0];
        unsigned char *end = &a[0] + (sizeof(a));

        std::copy(begin, end, std::ostream_iterator<unsigned char>(outfile));

        std::cout << "Writing file with ostream_iterator: " << std::endl;
        for (unsigned char *a = begin, *b = end; a != b; a++) {
            std::cout << std::hex << static_cast<int>(*a) << " ";
        }
        std::cout << std::endl;

        outfile.flush();
        outfile.close();
    }

    // This block of code doesn't produce the same output as
    {
        std::ifstream infile;
        infile.open("test", std::ios::binary);

        std::vector<unsigned char> myVec;

        infile.seekg(0, std::ios::end);
        myVec.resize(infile.tellg());
        infile.seekg(0);

        std::copy(std::istream_iterator<unsigned char>(infile), std::istream_iterator<unsigned char>(), 
                myVec.begin());

        std::cout << "Data read with istream_iterators: " << std::endl;
        for (std::vector<unsigned char>::iterator a = myVec.begin(), b = myVec.end(); a != b; a++) {
            std::cout << std::hex << static_cast<int>(*a) << " ";
        }
        std::cout << std::endl;

        infile.close();
    }

    // This block of code ...
    {
        std::ifstream infile;
        infile.open("test", std::ios::binary);

        std::vector<unsigned char> myVec;

        char a;
        while (infile.read(&a, 1)) {
            myVec.push_back(static_cast<unsigned char>(a));
        }

        std::cout << "Data read with .read(): " << std::endl;
        for (std::vector<unsigned char>::iterator a = myVec.begin(), b = myVec.end(); a != b; a++) {
            std::cout << std::hex << static_cast<int>(*a) << " ";
        }
        std::cout << std::endl;

        infile.close();
    }

    // Yet I would expect them to have the same result. Both should be reading from the input file, 
    // and copying it to the vector.

    return 0;
}