void binary(int number,int count=0) {
  int remainder;
 
  count++;
 
  if(number <= 1) {
    while(count % 4 != 0) {
      cout << '0';
      count++;
    }
    cout << number;
    return;
  }
 
  remainder = number%2;
  binary(number >> 1, count);
  if(count % 4 == 0)
    cout << ' ';
  cout << remainder;
}

#include <iostream>
 
using namespace std;
 
void binary(int number,int count=0) {
...
}
 
int main () {
	binary(0);
	cout << endl;
	binary(0xFF);
	cout << endl;
	binary(9872);
	cout << endl;
}