Pi is to be used to six decimal places and the value will be taken as pi = 3.14158

Firstly, list the plan structure as below. We suggest you download a copy of this structure and keep for future reference. It is the KEY to good planning. Remember PST (and structure has the three computing stages of input process and output). Click here to get a copy of this structure.

Programming - Planning

Purpose (What the program does)

Structure (How the program will do it)

• Input - What does the program need to get
• Process - What will it do with that information
• Output - What will the program give back to the user

Testing (Corrections and improvements)

Save the downloaded document as PlanningStructure to your Programming folder. Then re-save (F12) as AreaOfCirclePlan. Now we need to flesh the skeleton structure out. We have included 'constraints' in our Purpose part of the plan. A constraint is something that must be done you don't have to use the term if you are not familiar with it, just make sure you have listed any limitations or specific criteria (things) your program needs to do.

The title should reflect the nature of the program. Try to write your own plan from the brief and then check back with ours below.

Planning - Program To Find Area Of Circle

Purpose (What the program does)

The program needs to get the radius of a circle and display the area of the circle for that given radius. Formula: area = radius * radius * pi

CONSTRAINTS:

1.The user must be able to enter any type of data and the program will give the area back in that measurement type.

2. The program should be self explanatory. The user must know what to do without asking for help.

3. pi = 3.14158.

Structure (How the program will do it)

Input - What does the program need to get

The program needs to get the radius of the circle

The program needs to get the unit of measurement of the circle

Process - What will it do with that information

The program needs to multiply the radius by its self and then by pi, given formula below

area = radius * radius * pi

Output - What will the program give back to the user

The program needs to display the area of the circle and the unit of measurement.

Testing (Corrections and improvements)

You should have a completed program plan. We will now move on to the code. Below the structure in you planning document we are going to write a draft or pseudocode. This just means that we are going to start to write an order to our program in a language somewhere between English and code. There are NO written laws about the language of pseudocode whatever makes sense to you is fine. The goal is to organise the program into a logical order for things to happen. I use a numbered list, I find this helps to set the order.

The code comes from the structure part of the plan. We also need to start and end the program.

Skeleton Plan

1. Begin Program
2. Get Input
3. Process Input
4. Display Output
5. End Program

Copy the pseudocode below to the bottom of your plan - save and read through.

'Fleshed Out' Plan

1. Begin prog
2. Tell user how to use program
3. Get radius of circle
4. Get unit of measurement
5. Process: radius x radius x 3.14158 = area
6. Display area
7. Display unit of measurement
8. End program

Pseudocode

1. Sub Main
2. Radius= Input "This program will give you the area of a circle from the size of the radius. Please enter radius below"
3. Unit=Input"Please enter unit of measurement"
4. area=radius*radius*3.14158
5. msgBox"The area of the circle with " Radius & Unit " is " Area & Unit.
6. End program

If we entered the pseudocode into the the code window it would NOT work, it is false code a half way step between your plan and the full code. The full code is listed below. Copy the code to your new module window - run it and save. Now indent the code and put the REMs in as per the picture below. Run the program and check calculations with a calculator.

CODE

Option Explicit
Sub Main()
Dim radius, area As Double
Dim unit As String
radius = InputBox("This program will give you the area of a circle from the size of the radius. Please enter radius below")
unit = InputBox("Please enter the unit of measurement")
area = radius * radius * 3.14158
MsgBox "The area of a circle with radius " & (radius) & (unit) & " is: " & (area) & (unit)
End Sub

Make you code look as below.

Note we have used 'Double' as our variable type for the radius and the area. We want no restrictions on the size of the number our user can safely enter. The unit of measurement is a string since no mathematical functions will need to be applied to this. It is just a list of characters we will reproduce. We have also added the string '^3' to the end of the last message box since the final measurement will be cubed.

Check you program runs, If not it will be a typing error. Visual Basic is NOT case sensitive but it does need the correct spellings and all REM comments must have the ' before them. If you are having problems - Check the following

1. All lines of code are on ONE line in the module window
2. All REMs have a ' at the beginning
3. The program has the correct begin and end
4. All variable names are spelt correctly. Variables declared MUST be spelt the same as the variable used.
5. All message boxes have the correct spelling and layout (brackets, speech marks, commas etc.)
6. All input boxes have the correct spelling and layout (brackets, speech marks, commas etc.)
7. All variables are declared correctly, you cannot declare radius as a string and expect radius * radius to give you the correct answer.
8. Finally if you can see nothing wrong, close without saving and start again with a NEW VB6 program and module.

Using Shapes to Plan

As well as using a numbered list and pseudocode you can also use shapes to plan. The advantage of using shapes is it is quicker and easier to see errors in your logic. There are 3 basic shapes we use.

• A parallelogram for input and output
• A hexagon for a decision such as the if statement in the program that played the 'fixed game' - 2 or more choices possible.
• A rectangle for any other process (such as multiplying the radius by itself and then pi above) called a sequence.

It is a good idea to try to learn what the shapes represent and they are pictured below

A construct shape diagram - a shape plan for this program is shown below. What the program does is shown in a rectangle at the top. Then the program shows what happens by moving through the shapes form left to right. So this program

1. Gets the Radius (input)
2. Gets the unit of measurement (input)
3. Uses a mathematical sequence to get the area (sequence)
4. Displays the area and unit back to the user.

Once you are happy with your progress click the QUIZ button.