The Inside IF

The program is nearly finished. All we need to do now is to fill in the part of the program that decides between the two discount rates.

PRINT "Please enter the base rate"
INPUT BASERATE

PRINT "Please enter annual mileage"
INPUT MILEAGE

IF MILEAGE < 20000 THEN

  Decide between 5% and 10% discount

ELSE
  LET DISCOUNT = 0.0  ' no discount for high milage cars
END IF

PRINT "Your base rate is", BASERATE
PRINT "Your discount is", DISCOUNT
PRINT "You pay", BASERATE * (1 - DISCOUNT)

END

This part of the program will be a nested IF (sometimes called an inner IF because it is nested inside the first one.) It will decide between two cases:

• A 5% discount applies to cars driven less than 20,000 miles a year.
• A 10% discount applies to cars driven less than 10,000 miles a year.

There are several equally good ways that this inner IF could be written. Here is one way:

IF MILEAGE < 20000 THEN
 
  IF car gets 10% rate THEN
    LET DISCOUNT = .1
  ELSE
    LET DISCOUNT = .05
  END IF

ELSE
  LET DISCOUNT = 0
END IF