Learn to Program with Small Basic

Random Numbers
Random numbers are used in many applications, like simulations and games.
They’re also used for software testing (to see how a program responds to
different input values) or to simulate random events (like the lottery).
The GetRandomNumber() method returns a random integer between one
and the upper limit you pass to the method. Using this method, your program
can generate random numbers that you can use in all sorts of exciting
applications, for instance, to see whether a troll bops your hero on the
head. Let’s look at some examples.
To simulate a roll of a die, write this:
dice = Math.GetRandomNumber(6)
TextWindow.WriteLine("You rolled: " + dice)
The variable, dice, contains a number between 1 and 6 that’s selected
at random, similar to picking it out of a hat (but not the Hogwart’s Sorting
Hat). Run the program several times to see for yourself.
To simulate the flip of a coin, you can write this:
coinFlip = Math.GetRandomNumber(2)
TextWindow.WriteLine("Outcome: " + coinFlip)
The variable coinFlip is either 1 or 2. The value 1 represents heads, and
the value 2 represents tails (or the other way around; it’s up to you!).
To simulate rolling a pair of dice and finding their sum, you can write
this code:
num1 = Math.GetRandomNumber(6)
num2 = Math.GetRandomNumber(6)
outcome = num1 + num2
TextWindow.Write("You got (" + num1 + "," + num2 + "). ")
TextWindow.WriteLine("The total is " + outcome)
Although your outcome will be a number between 2 (rolling two 1s)
and 12 (rolling two 6s), don’t make the mistake of writing this:
outcome = 1 + Math.GetRandomNumber(11)
Although this statement gives you a number between 2 and 12, the
probability you’d get from one random number is different from adding
two random numbers together.
TRY IT OUT 7-5
A bag contains 20 balls numbered from 1 to 20. Write a program that simulates
drawing one ball from the bag at random.
92 Chapter 7