Sorting digits of an integer

Question

You are given an integer 51234 (say) we need to sort the digits of a number the output will be 12345.

How to do it without using array ?

Answer 1

// Bubblesort
long sortNum(long n) {
  while (true) {
    long a = n % 10, p = 9;
    bool s = false;
    for (long r = n / 10; r; r/= 10) {
      long b = r % 10;
      if (a < b) {
        n -= p * (b - a);
        s = true;
      } else a = b;
      p *= 10;
    }
    if (!s) return n;
  }
}

#include 

int main(int argc, char **argv) {
  if (argc > 1) {
    long n = strtol(argv[1], 0, 0);
    std::cout << "Unsorted: " << n << std::endl;
    n = sortNum(n);
    std::cout << "Sorted:   " << n << std::endl;
  }
  return 0;
}

$ g++ -Wall -Wextra bubble-int.cpp && ./a.exe 183974425
Unsorted: 183974425
Sorted:   123445789