#include <bits/stdc++.h>
using namespace std;
const int sz= 101;
bool visited[sz];


class Customer
{

    int id ;
    char name[20];

public :

    bool searchId(int val)
    {
        ifstream in ("data.txt", ios:: in);

        if(in.is_open())
        {
            Customer c1;

            while(!in.eof())
            {
                in.read( (char *)& c1, sizeof(c1));
                if(c1.id== val) return true;
            }

        }
        else cout << "Cann't open the file ";
        in.close();

        return false;
    }

    bool validId( double val){

       return ( val > 0 and int(val)== val  and (!searchId(val) or !visited[int(val)] )) ;
     }


    void setId()
    {
        double x ;
        cout << "Enter ID : ";
        cin >> x;


        while(!validId(x) )
        {
            cout <<"Invalid Id , please try again \n";
            cout << "Enter ID : ";
            cin >> x;

        }
        id = int(x);
        visited[id]= true;

    }

    int getId()
    {
        return id;
    }

    void setName()
    {
        cout << "Enter name : ";
        cin >> name ;
    }

    char* getName()
    {
        return name;
    }
};


int main()
{

for(int i=0 ; i<sz ;i++) visited[i]= false;

    Customer c1 ;
    ofstream out("data.txt", ios::out | ios::app );
    char ch='Y';
    do{
        c1.setId();
            visited[c1.getId()] = true;
        c1.setName();
        out.write( (char *)&c1 , sizeof(c1));
        cout <<"press Y to continue";
        cin >> ch ;

    }while(ch=='Y');

    out.close();

    return 0;
}