Ms. Payne, WCSS. This is very much like asking a question, and having a yes/no answer (also known a true/false). The general structure for this is:

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Allison Clark
5 years ago
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1 The Decision Structure The repetition (looping) structure discussed previously is a very important structure because it allows the programmer to instruct the computer to do something more than once. The decision structure is also very powerful. A decision structure is used to determine if a specific action should be taken. It allows different actions to be taken depending on the circumstance. Decision structures have four parts. If, then,, end if. Lets look at an example written in plain English: if it is after midnight then go to bed keep partying end if This is very much like asking a question, and having a yes/no answer (also known a true/false). The general structure for this is: if some condition then - statements to be executed when the condition is true. - statements to be executed when the condition is false end if

2 Here s an example where the user is asked the Capital of Ontario. answer = "" exit = 0 While exit = 0 TextWindow.WriteLine("Please enter in the capital of Ontario") answer = TextWindow.Read()'reads user input (can be with spaces) if answer = "Toronto" then TextWindow.WriteLine("Correct") exit = 1 TextWindow.WriteLine("Try again") endif EndWhile 'exits loop when answer is correct 'loop repeats until correct answer Here is another example where a user entered in two numbers and then entered the sum. The program then checks to see if their sum is correct. TextWindow.WriteLine("Please enter the first number:") number1 = TextWindow.Read() TextWindow.WriteLine("Please enter the second number:") number2 = TextWindow.Read() TextWindow.WriteLine("Please enter the sum of "+number1+" and "+number2+":") total = TextWindow.Read() if total = number1 + number2 then TextWindow.WriteLine("Congratulations, that is correct") TextWindow.WriteLine("Check your answer.") Endif

3 If you want to do more than one comparison you use if for every check after the first if. For example, here s a program that has the user enter in a number, and then it checks to see if the number is positive, negative or zero. TextWindow.WriteLine("Please enter a number:") number = TextWindow.Read() if number > 0 then TextWindow.WriteLine("positive") if number < 0 then TextWindow.WriteLine("negative") TextWindow.WriteLine("zero") endif Here I have also introduced different ways to compare things. You use the following syntax to computer two values in an if--then statement: < less than > greater than <= less than or equal to >= greater than or equal to <> not equal

4 Activity #1: Write a program that has the user enter in their age, and then based on their age you output a movie price. This program should repeat for multiple users. Here is the pseudo code: Get users age If they are 65 or older Pay $3.00 as you are a senior If they are 20 or older Pay $6.00 as they are an adult If they are 14 or older Pay $3.00 as they are a student If they are younger then 14 Pay $2.00 as they are a child. Activity #2: Create a conditional if statement that allows the user to pick a favourite colour, and then will output a circle of that colour. Activity #3: Create a multiple choice quiz or game using If Statements

5 AND and OR We can use AND and OR statements in our if-then- statements to look at multiple ranges or options for each action. For example, a way to complete the previous activity would be to use and statements to declare an age range. In this case I have used two comparisons split by an and but it is possible to use more than two as well. TextWindow.WriteLine("Please enter an age:") age = TextWindow.Read() If age>=0 And age<13 Then TextWindow.WriteLine("You are a child.") ElseIf age>=13 and age<20 then TextWindow.WriteLine("You are a teen.") if age>=20 and age <65 then TextWindow.WriteLine("You are an adult.") if age>65 and age<=115 then TextWindow.WriteLine("You are a senior.") Else TextWindow.WriteLine("Invalid age.") EndIf

6 In many cases we would also like to do comparisons where a reaction happens in the case of many individual options. For example, proper coding would be to check each possible user input ( a, A ) for the following questions. Start: TextWindow.WriteLine("Pick a favourite colour: ") TextWindow.WriteLine("a) Red") TextWindow.WriteLine("b) Blue") TextWindow.WriteLine("c) Green") TextWindow.WriteLine("d) Yellow") TextWindow.WriteLine("e) Orange") Choice = TextWindow.Read() If Choice = "a" Or Choice = "A" Then Color = "red" ElseIf Choice = "b" Or Choice = "B" then Color = "blue" ElseIf Choice = "c" Or Choice = "C" then Color = "green" ElseIf Choice = "d" Or Choice = "D" then Color = "yellow" ElseIf Choice = "e" Or Choice = "E" then Color = "orange" Else TextWindow.WriteLine("Try Again") Program.Delay(2000) TextWindow.Clear() Goto Start EndIf TextWindow.Hide() GraphicsWindow.Show() GraphicsWindow.Height = 400 GraphicsWindow.Width = 400 GraphicsWindow.BrushColor = Color Circle = Shapes.AddEllipse(100,100) Shapes.Move(Circle,150,150) Even better programming would be to check for all possibilities ( a, A, red, Red ) such as the following line: If Choice = "a" Or Choice = "A" Or Choice = "red" Or Choice = "Red" Then

7 Activity #1: Develop a program that compares the # of hours of playing video games a week against the following scale: less than 2 hours is "too little" between 2 hours and 4 hours is "normal" between 4 hours and 8 is "excessive" more than 8 hours is "ridonculous!" Activity #2: Write a program that give the user feedback of "higher" or "lower" until the user correctly guesses a randomly generated number between 1 and 100. Activity #3: Create a simple trivial-pursuit-type game with questions that keeps a score as the user works through the game.

Repetition Algorithms

Repetition Algorithms Repetition Allows a program to execute a set of instructions over and over. The term loop is a synonym for a repetition statement. A Repetition Example Suppose that you have been