EnableExplicit

Procedure.i count_bits(v.i)
  Define c.i
  While v
    c+v&1
    v>>1
  Wend
  ProcedureReturn c
EndProcedure

If OpenConsole()
  Define n.i
  For n=0 To 255
    Print(Str(count_bits(n)%2))
  Next
  PrintN(~"\n...fin") : Input()
EndIf