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Figure 6-7 shows two sample outputs for when the user enters 6 and 9,
respectively, in response to the ask command. Can you explain how this
script works?

Nested if and if/else Blocks

If you want to test more than one condition before taking an action, you
can nest multiple if (or if/else) blocks inside each other to perform the
required test. Consider for example the script shown in Figure 6-8, which
determines whether a student should receive a scholarship. To qualify, the
student must have: (1) a grade point average (GPA) higher than 3.8 and (2)
a grade above 92 percent in math.

No gpa Yes mathScore
> 3.8? > 92?
No Yes
say
“Sorry! Low say say
GPA.” “Sorry! Low “Congratulations!”
math score.”

Figure 6-8: You can use nested if/else blocks to test multiple conditions .

First, the expression gpa > 3.8 is tested. If this expression is false, we
don’t need to check the other condition because the student doesn’t meet
the scholarship criteria. If the expression gpa > 3.8 is true, however, we
need to test the second condition. This is done with the nested if/else block,
which tests the condition mathScore > 92. If this second condition is also
true, the student gets the scholarship. Otherwise, the student does not qual-
ify, and an appropriate message explaining the reason is displayed.

Menu-Driven Programs

AreaCalculator Next, we’ll explore a typical use of nested if blocks. In particular, you’ll
.sb2 learn how to write programs that present the user with choices and act on
the user’s selection.
When you start up some programs, they display a list (or menu) of avail-
able options and wait for you to make a selection. Sometimes, you’ll interact
with these programs by entering a number that corresponds to your desired
option. Such programs may use a sequence of nested if/else blocks to deter-
mine the user’s selection and act appropriately. To see how nested if/else
blocks work, we’ll discuss an application, shown in Figure 6-9, that calcu-
lates the area of different geometric shapes.

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