Decimal to Binary program, need feedback

#include <iostream>
#include <vector>
#include <string>
#include <iterator>
#include <fstream>
#include "modeset.h"
#include <locale>
#include <sstream>


using std::cout;
using std::cin;
using std::vector;
using std::string;
using std::endl;
using std::cerr;
using std::stringstream;


int convert_to_bin(int user_conv_num)
{
    stringstream bin_in_string;//stringstream to store int result in

    if(user_conv_num == 0)
    {

        return 0;

    }


     convert_to_bin(user_conv_num / 2);//We call convert_to_bin function while dividing user_conv_num in the parameter because the modulus operator does not divide for us


     bin_in_string<<user_conv_num % 2;//Get the reminder using the modulus operator, this does not divide user_conv_num by two, it only gets the remainder and writes it to bin_in_string


     cout<<bin_in_string.str();//print result

     return 0;
}

int main()
{
    long int user_conv_num = 0;


cout<<"(#)";

cin>>user_conv_num;


    try
    {


      if(user_conv_num < 0) //if negative number
        throw 1; //throw int exception


      else
        {

        convert_to_bin(user_conv_num); //if not a negative number , do the conversion

        }

    }

    catch (int) //catch int exception if true
    {

        cerr<<"Negative integer";

    }

}