Decimal to Binary

#include <iostream>
#include <cmath>

using namespace std;
long long convert(int);
long long convert(int n) {
  long long bin = 0;
  int rem, i = 1;
  while (n!=0) {
    rem = n % 2;
    n /= 2;
    bin += rem * i;
    i *= 10;
  }
  return bin;
}