How to read and write in text file in c++

#include<iostream>
#include<conio.h>
#include<fstream>
using namespace std;
int main()
{
 char name[100];
int roll;
 cout << "Enter name: ";
      cin>> name;
      cout << "Enter Roll: ";
      cin>> roll;
      ofstream file;
      file.open("file.txt",ios::app);
    if(file.is_open())
    {
   
      file<< name<< roll<< endl;
}
      file.close();
 ofstream file2;
 char n[100];
 file2.open("file.txt",ios::in);
 cout << "Enter name : ";
 cin >> n;

 if(strcmp(n,name)==0)
 {
            cout << name <<":" << roll;
            }
            file2.close();
      getch();
      return 0;                
    }