read.cpp

int main() 
  { 
    int x; 
    ifstream infile; 
    infile.open("silly.dat", ios::binary | ios::in) 
    infile.read(&x, 7); // reads 7 bytes into a cell that is either 2 or 4 
  } 

write.cpp

struct Person
{
  char name[50];
  int age;
  char phone[24];
};

int main()
{
  Person me = {"Robert", 28, "364-2534"};
  Person book[30];
  int x = 123;
  double fx = 34.54;
  ofstream outfile;
  outfile.open("junk.dat", ios::binary | ios::out);
  outfile.write(&x, sizeof(int)); // sizeof can take a type
  outfile.write(&fx, sizeof(fx)); // or it can take a variable name
  outfile.write(&me, sizeof(me));
  outfile.write(book, 30*sizeof(Person))
  outfile.close();
}