int bufsize    = 8;
char* buffer   = "        \n";
char* newline  = "\n";

int Zahl  = 9;
int i     = bufsize;
do {
  i = i - 1;
  buffer[i] = (Zahl % 2) + '0';
  Zahl = Zahl / 2;
} while ( Zahl != 0 );

output(buffer);