#include <iostream>
#include <fstream>

template <typename T>
void read(std::istream &stream, T &ref)
{
    stream.read(reinterpret_cast<char*>(&ref), sizeof(T));
}

template <typename T>
void write(std::ostream &stream, const T &ref)
{
    stream.write(reinterpret_cast<const char*>(&ref), sizeof(T));
}

int main()
{
    {
        std::fstream file("test.bin", std::fstream::out | std::fstream::binary);

        int i = 42;
        write(file, i);
    } // will close file

    {
        std::fstream file("test.bin", std::fstream::in | std::fstream::binary);

        int i;
        read(file, i);
        std::cout << "i = " << i << std::endl;
    }

    return 0;
}