FORTHEX/forth_scripts/calculator.forth at main · arturz/FORTHEX · GitHub

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VARIABLE calculator-accumulator

: CALCULATOR-SHOW-MENU
  PAGE
  ." =============================" CR
  ."      FORTH CALCULATOR       " CR
  ." =============================" CR
  ."  Value: " calculator-accumulator @ . CR
  ." =============================" CR
  ." Available options (0-7):" CR
  ."  1. Set value" CR
  ."  2. + (add)" CR
  ."  3. - (subtract)" CR
  ."  4. * (multiply)" CR
  ."  5. / (divide)" CR
  ."  6. Clear (0)" CR
  ."  7. Quit" CR
  ." =============================" CR ;

: CALCULATOR
  0 calculator-accumulator !

  BEGIN
    CALCULATOR-SHOW-MENU
    ."  Choice > " ACCEPT

    DUP 7 = IF
      DROP TRUE
    ELSE
      DUP 1 = IF DROP ."  Enter new value: " ACCEPT calculator-accumulator ! ELSE
      DUP 2 = IF DROP ."  Add: " ACCEPT calculator-accumulator @ + calculator-accumulator ! ELSE
      DUP 3 = IF DROP ."  Subtract: " ACCEPT calculator-accumulator @ SWAP - calculator-accumulator ! ELSE
      DUP 4 = IF DROP ."  Multiply by: " ACCEPT calculator-accumulator @ * calculator-accumulator ! ELSE
      DUP 5 = IF DROP ."  Divide by: " ACCEPT calculator-accumulator @ SWAP / calculator-accumulator ! ELSE
      DUP 6 = IF DROP 0 calculator-accumulator ! ELSE
        DROP
      THEN THEN THEN THEN THEN THEN
      FALSE
    THEN
  UNTIL

  PAGE
  RESET-TERMINAL
  BANNER ;

CALCULATOR