; A loop: add numbers until the user enters 0

PROC Main()
  CARD sum, number

  sum=0
  PrintE("Enter numbers, 0 ends.")
  DO
    Print("? ")
    number=InputC()
    IF number=0 THEN
      EXIT
    FI
    sum==+number
  OD

  PutE()
  Print("The sum is ")
  PrintCE(sum)
RETURN