How Nested IFs Work

Say that the user starts the program and wants coffee for breakfast. The monitor screen will look like this:

Do you want coffee? (Answer YES or NO)
? YES
Your beverage costs:   1.05

Here is how the program ran. The statements are numbered in the order that they executed:

(1) PRINT "Do you want coffee? (Answer YES or NO)"
(2) INPUT ANSWER$

(3) IF ANSWER$ = "YES" THEN  <-- true
(4)   LET PRICE = 1.05       <-- true branch is executed

    ELSE
      ' decide between tea and milk                |
      PRINT "Do you want tea? (Answer YES or NO)"  |
      INPUT ANSWER$                                |
                                                   |
      IF ANSWER$ = "YES" THEN                      | <-- false branch is skipped
        LET PRICE = 1.50                           |
      ELSE                                         |
        LET PRICE = .89                            |
      END IF                                       |

    END IF

(5) PRINT "Your beverage costs:", PRICE
(6) END

The first true/false expression ANSWER$ = "YES" gave an answer of true so the true branch was executed.