///////    File octdisp.C    ///////
#include <iostream.h>

const int DIG = 20;
const int LOWDIGIT = 07;   // least significant octal digit mask 

void octal_display(register int x)
{ register int i = 0;
  char s[DIG];
      if (x < 0)            
      {   cout.put('-'); 
          x = -x;
      }
      do {  s[i++] = ((x & LOWDIGIT) + '0'); // mod performed with &
         }  while ( ( x >>= 3) > 0 );        // divide x by 8 via shift
      cout.put('0');
      do {  cout.put(s[--i]);
         }  while ( i > 0 );
      cout.put('\n');
}

int main()
{    octal_display(0);
     octal_display(-1);
     octal_display(0123456);
     octal_display(-0123456);
     octal_display(999);
     octal_display(-999);
     octal_display(2978);
}