Software Development

  Assignment 3 Guide

Implementation Phase - Overview

These notes give an overview of how to tackle your Assignment 3 program code.

Introduction

The Assignment

The Whole Picture

Introduction

Objectives

This guide  will help you to: -  

·   think about how to go about implementing your program

·   describe how you could structure your program code

If you need to you should print out the following two assignment documents.

Assignment Scenario

Assignment 3: Implementation

As with your previous assignments, Assignment3 is concerned with the Lawnsword Garden Design Company. 

The documentation you need to produce is listed below.

In this assignment you will use your design documents from Assignment 2 to help you create and test the program. You will need to create your input and output forms, then create the program code and then test your program.

The Whole Picture

Before diving in and creating program code it is always best to have a good idea on how you are going to structure your program. This means thinking about the inputs, stored data, outputs.  For a VB program the structure of your program will be also be influenced by user events, (events like the user clicking a command buttons etc.) In other words..

• some parts of your code will need to execute straight away when the program loads

• some parts will execute only when the user type in inputs and clicks a submit button.

When thinking about how to structure your program code, you need to think about sequences of events. The diagram below illustrates the different parts of the program.  Hover the mouse over the link below it to see where each part could be coded for in VB. 

VB Code Structure

Starting with Step 1, the code for setting the values of the stored data could be carried out inside the input forms Load sub routine.

At Step 2, the program needs to get the user's input. The code for getting the inputs could be placed inside the Click sub routine for a Submit button or equivalent.

At Step 3, the program needs to carry out the calculations.  The code for this could be placed inside a separate sub routine  -  perhaps called something like calculate.

At Step 3, the program needs to display the results.  The code for this could be placed inside the output forms Load sub routine.

The diagram below shows the VB sub routines in more detail.

If you hover you mouse over a link or click on it, you will see details on the sub routine and code that could be used to carry out each part.

Step 1: Stored Data   Step 2: Get Inputs  Step 3: Calculate   Step 4: Display Results

Now it's your turn. Carry out the activity below. It will help you to add all the forms and modules you will need to your project. It will also help you create the basic code sub routines ready for later.

~~Activity~~

Activity A

First, open up Visual Basic and start a new project. Step 1 - Stored Data Double-click the form, this will take you to the coding window.  Copy the following code.. Private Sub Form_Load()         ' code goes here that executes when the program first starts         ' e.g. set the values of the stored data variables ready to use later on End Sub Step 2 - Get Inputs Now add a command button to your form.   Name it cmdSubmit. Double-click the command button, this will take you to the coding window.  Copy the following code.. Private Sub cmdSubmit_Click()         ' the user clicks the command button         ' code goes here that gets the values from the input textboxes End Sub Step 3 - Calculate Now double-click the form, again  Copy the following code.. Private Sub calculate()         'code goes in here that does all the calculations End Sub Step 4 - Display Results Now add a second form to your project.  You can do this by clicking Project on the menu and then Add Form. Double-click the form, this will take you to the coding window.  Copy the following code.. Private Sub Form_Load()         'code goes here that display the results in labels End Sub Add Module for Declaring Variables Finally, add a module to your project.  You can do this by clicking Project on the menu and then Add Module. Copy the following code into the module.. 'stored data variables 'input variables 'output data variables You should end up with your project explorer showing 2 forms and a module. When you have finished by clicking the save button.   VB will ask you to save both your forms, the module and the project.  Make sure you save them all to the same folder.

So far I have given you a general structure for your seed calculation program. If you carried out Activity A you will now have a basic structure from which you can start coding properly. To help you along a little further, you can look at the same coding structure here - I have added a few lines of example code here and there.

~~Activity~~

Activity B

Saving Your Work It is important that you save your VB work properly.  There are a few important points to consider... Each separate form is saved into a separate form file. If you lose your form file, you will have to create a new one.  There is no way around this. Each separate module is saved into a module form file. If you lose your module file, you will have to create a new one.  There is no way around this either. The project file just hold information about your project, such as what forms files or module files VB should include in your project. If you lose your project file, you can create a new one.  Try the following.. Go to the folder where you saved your VB work.  Double-click any form file.  What happens? Close VB and don't save anything if it asks.  Now double-click the project file.  What happens? Close VB and don't save anything if it asks.  Move one of your form files to a different folder, then we can pretend you deleted it by mistake. Now double-click the project file.  What happens? Close VB and don't save anything if it asks.  Move your form file back to where it was.

 

Your Task

Before going any further with the coding, you need to create your GUI - your input and output forms. This tutorial covers that.

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