#include<iostream.h>
#include<fstream.h>
void main()
{
char c;
cout<<"choese"<<endl;
cout<<"[a]add     [m]modifay   [d]display"<<endl;
cin>>c;

if(c=='a')

{

	fstream io;

	char name[20];

int rollno;

io.open("s.text",ios::app|ios::out|ios::in);

cout<<"enter name"<<endl;cin>>name;
io<<name;io<<"         ";


cout<<"enter roll no: ";cin>>rollno;

io<<rollno;

io<<endl;

}

if(c=='m'){
fstream io;
	char name;
int rollno,rn;
long loc;
io.open("s.text",ios::app|ios::out|ios::in);

cout<<"enter number modefy"<<endl;
cin>>rn;

do{

	io>>rollno;
	loc = io.tellg();
	if(rn==rollno)break;
	io>>name;
}

while(!io.fail());
	if(rollno !=rn)
		cout<<"not exist"<<endl;
	io.seekp((loc-1),ios::beg);
	io<<rn;

}

if(c=='d'){
		fstream io;

	char name[20];

int rollno;

	io.open("s.text",ios::out|ios::in);
io>>name;
cout<<name;
cout<<"       ";
io>>rollno;
cout<<rollno;
}

}