Prime Numbers

[rockx]

I have tweeked the code a little bit more. And i know it could furthter be improved

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <cmath>
using namespace std;

int main()
{
long int	i = 1,
		c = 3,
		n,
		s,
		j;

  int input;
		cout << "Enter the Values to be calculated: ";
		cin >> input;

ofstream	myfile ("PrimeNumbers.doc");

	if (myfile.is_open()) {
		myfile << 1 << "=\t"  << 1 <<"\n\n";
		myfile << 2 << "=\t"  << 2 <<"\n\n";

		while (c <= input) {
			n = 0;
			i += 2;
			s = (long)sqrt((float)i);
			for (j = 2; j <= s; j++) {
				if (i % j == 0) {
					n += 1;			
					break;
				}
			}

			if (c >= (input-50))
			{
					myfile << c << "=\t"  << i <<"\n\n";
					c += 1;
			}
			else if (n == 0) {
			
				c += 1;
			}
		
		}
		myfile.close();
	} else
		cout << "Unable to open file";

	return 0;
}

And the question on analysis, well nothing tooo big and nothing too serious. and not really analysis, i might keep the record for future references, i dont really know when i might need them. If i get to learn to do something with it in the future then i guess this should be a good start off for me