Двоичный ввод-вывод

#include <fstream>
#include <iostream>
 
struct integer
{
    char integer_;
    int first;
    int second;
};
 
std::ostream& operator <<(std::ostream& os, const integer& integ)
{
    os << integ.integer_ << ' ' << integ.first << ' ' << integ.second << '\n';
    return os;
}
 
struct doubleger
{
    char doubleger_;
    double first;
    double second;
};
 
std::ostream& operator <<(std::ostream& os, const doubleger& doubleg)
{
    os << doubleg.doubleger_ << ' ' << doubleg.first << ' ' << doubleg.second << '\n';
    return os;
}
 
int main()
{
    std::ofstream ofs("f_name", std::ios::binary);
    if(!ofs)
    {
        return 1;
    }
    integer integ;
    integ.first = 5;
    integ.second = 100;
    integ.integer_ = 'i';
    doubleger doubleg;
    doubleg.first = 5.5;
    doubleg.second = 25.4;
    doubleg.doubleger_ = 'd';
 
    ofs.write((char*)&integ, sizeof(integer));
    ofs.write((char*)&doubleg, sizeof(doubleger));
    ofs.close();
    std::ifstream ifs("f_name", std::ios::binary);
    if(!ifs)
    {
        return 1;
    }
    while(1)
    {
        integer res_integer;
        doubleger res_doubleger;
        std::streambuf* pbuf = ifs.rdbuf();
        int s_int = pbuf->sgetc();
        if(s_int == -1)
            break;
        std::cout << (char)s_int << '\n';
        if(s_int == 'i')
        {
            ifs.read((char*)&res_integer, sizeof(integer));
            std::cout << res_integer << '\n';
        }
        else if(s_int == 'd')
        {
            ifs.read((char*)&res_doubleger, sizeof(doubleger));
            std::cout << res_doubleger << '\n';
        }
    }
}

streambuf * pbuf;
       pbuf = f2.rdbuf();
       while (pbuf->sgetc()!=EOF)
       {
          ch = pbuf->sbumpc();
          cout << ch;
       }

#include <iostream>
#include <fstream>
 
using namespace std;
 
int main()
{
    ifstream in;
    char c;
    
    in.open("file.txt", ios::binary);
 
    while (in.get(c))
        cout << c << " " << (c == 'a') << endl;
    in.close();
    return 0;
}

sizeof(mammal)