Agfdhyk

I have a problem that the part of the internet that I went through can't solve.
It's my very first encounter with fstream and no matter what I do the program won't import more than one integer from the text file. I'd love if anyone with knowledge could help me a little. Here is the code that I'm using at the moment.
Writing:

void writeVector(const std::vector<int>& vec, const std::string& fileName) {

std::ofstream save;

save.open(fileName);

if (save) {

    for (int i = 0; i < vec.size(); ++i) {

        save << &vec[i];

    }



std::cout << "Plik zapisano pomyslnie.n";

}

save.close();

}

Reading:

std::vector<int> readVector(const std::string& fileName) {

std::ifstream read(fileName);

std::vector<int> buffer;

if (read) {

    int value;

    while (read >> value) {

        buffer.push_back(value);

    }

}

return buffer;

}



void zad4() {

    std::string fileName = "Zadanie 2";

    print(readVector(fileName));

}

Plus what's bothering me is the code in the txt file since it is something like: (00000248EC48FE5000000248EC48FE5400000248EC48FE5800000248EC48FE5C etc).
When I print "buffer" it only gives me one number. I have made sure that the vector is correctly initialized. What can be the problem?

Short answer: (credit: Sam Varshavchik)

if (save) {

        for (int i = 0; i < vec.size(); ++i) {

            save << vec[i] << ' ';

        }

The data in the file looks like a string of hexadecimal values. Your attempt to read this data tries to read it using decimal. As it starts of with a decimal digit and the sequence of decimal digits don't exceed the maximal value for int the read attempt manages to get one value. That is almost certainly not what you'd actually want to do with this data.

Now, what to actually do with this data is a separate question. You may want to read suitable groups of hex characters into corresponding integers. Whether that is the correct thing to do depends on what the data is supposed to mean. There seems to be a repeating pattern in the section you quoted (rewritten with the string broke after 16 character/8 bytes):

00000248EC48FE50

00000248EC48FE54

00000248EC48FE58

00000248EC48FE5C

That seems to imply that the data contains some sort of 64 bit data spelled in hex. The formatted input used by IOStreams really likes to get spaces. One way to decode this data is to read it into a buffer with 16 characters, update a string stream with this data, and read data from there as hex data:

std::istringstream sin;

sin >> std::hex;

char               buffer[16];

while (read.read(buffer, 16)) {

    sin.str(std::string(buffer, buffer + read.gcount()));

    sin.clear();

    std::uint64_t value;

    if (!(sin >> value)) {

        break;

    }

    buffer.push_back(value);

}