Hi Ajay,
I modified your example (see below), and it works for me (GCC 3.1 on OS X).
Sincerely,
--Eljay
#include <fstream>
#include <iostream>
#include <cstdlib>
#include <cerrno>
using namespace std;
int main()
{
fstream iostrm;
iostrm.open("new1.txt", ios_base::out | ios_base::in);
cout << errno;
iostrm.write("gagan", 5);
iostrm.close();
return 1;
}