Beispiel:

#include <iostream.h>
#include <iomanip.h>
#include <fstream.h>

class A
{
public:
  A(int=0,int=0);
  friend ostream& operator <<(ostream&, A&);
private:
  int a, b;
};

A::A(int a1, int a2)
{
  a = a1; b = a2;
}

ostream& operator <<(ostream& s, A &a)
{
  return s << a.a << ' ' << a.b;
}



main()
{
  A obj(10,100), obj1;

  // von fstream kann zugleich gelesen und 
  // geschrieben werden!!
  fstream aFile;
  aFile.open("out.bin", ios::in | ios::out);
  streampos p = aFile.tellp();

  aFile.write((char*)&obj, sizeof(A));

  aFile.seekg(p);
  aFile.read((char*)&obj1, sizeof(A));
  cout << obj1 << endl;
  aFile.close();
}