file.seekg(0);

#include "stdafx.h"
#include <iostream>
#include <fstream>
using namespace std;
 
class name
{
    char n[1000];
public:
   // name(string N=""):n(N) {}
    char* getName()
    {
        return n;
    }
};
 
int _tmain(int argc, _TCHAR* argv[])
{
    fstream file("data.dat",ios::in | ios::out | ios::binary);
    name N;
    file.read(N.getName(),1000);
    if(!file.fail())
        cout << "Good!";
    getchar();
 
    return 0;
}
 

class item{
public:
	item(){ID=0;}
	item(int,string,unsigned short int num,double);
	item(const item &);
 
	int showId() const {return ID;}
 
	void changeName(string Name);
	string getName() const {return name;}
	void changeNum(unsigned short int Num);
	unsigned short int getNum()const{return num;}
 
	void changeMoney(double Money);
	double getMoney() const {return money;}
 
	int getId()const{return ID;}
private:
	int ID;
	string name;
	unsigned short int num;
	double money;
};

file.seekg((sizeof(int)+1000+sizeof(unsigned short int)+sizeof(double))
file.read(id,sizeof(int))*numero_de_registro);//id=int
file.read(name,1000);//name=char[1000]
...
 

char id[sizeof(int)];
file.read(id,sizeof(int));

	fstream file("data.dat",ios::out | ios::binary);
	name n;
	char text[100]={"cosa"};
	int numero=2;
	file << text << ' ';
	file.write((char*)&numero,sizeof(int));

	fstream file("data.dat",ios::in | ios::binary);
	name n;
	char text[100];
	int numero;
	file >> text;
	file.read((char*)&numero,sizeof(int));