Learn to Program with Small Basic

Simplifying Expressions
Variables can make calculating arithmetic expressions easier. Let’s say you
want to write a program that evaluates this expression:
1 5
+ 5 7
7 8
− 2 3
You can write a bunch of different programs that would all give you the
right answer. For example, you could write a statement that evaluates the
whole expression at once:
TextWindow.WriteLine((1 / 5 + 5 / 7) / (7 / 8 - 2 / 3))
Or you might evaluate the numerator and the denominator separately
and then display the result of their division:
num = (1 / 5) + (5 / 7) ' Finds the numerator
den = (7 / 8) - (2 / 3) ' Finds the denominator
TextWindow.WriteLine(num / den) ' Does the division
You could also evaluate each fraction separately and then display the
result of the combined expression:
a = 1 / 5
b = 5 / 7
c = 7 / 8
d = 2 / 3
answer = (a + b) / (c - d)
TextWindow.WriteLine(answer)
Although these three programs give you the same answer, each program
uses a different style. The first program is the “chubby bunny” of programming:
it crams everything into one statement. If the original expression was
more complex, the statement would be really hard to follow. The third program
does the opposite: it represents every fraction in the expression with a
variable, and that can also be hard to read.
If you’re Goldilocks, the second solution is your “just right.” It breaks
down the expression into just enough parts to make the program easier to
understand. The variables num and den clearly represent the numerator and
the denominator.
As these examples show, there’s often more than one way to solve a problem.
If you ever get stuck on a problem, try breaking it into more manageable
pieces!
50 Chapter 4