CSI 101 Elements of Computing – Spring 2009

Lecture #11 – Structures of Visual BasicWednesday, March 18th

Visual Basic Form

Primary means for user to interact with VB application

Contains Windows constructs to hold particular information We will discuss those later

Most applications have more than one form Particular events cause a new form to open

Parts of a Form

Title Menu Bar

Contains words Produces dropdown menus

Tool bar Contains icons

Status bar Bottom Contains messages or other information

Example of Parts of a Form

Types of Forms Splash page

First screen to appear Main Menu (Switchboard)

Provides paths to major functions Most applications have screen menus as well

as menu bars Easy to follow logical path to get to particular

function Data Entry Reporting/Data Display

Splash Page Example

Main Menu – Simple Example

Main Menu - Functional

Submenu – Simple Example

Branch Manager Selector ToolSearch Specifications

Which best describes selection requirements?Find competitor branches near PNC branch

Find branches near specific competitorº

º

Results

Should headquarters be included in search results?º No (default)º Yes

What about Denovo competitive branches?

IncludeExclude (default)

Only show Denovo

º

ºº

How many branches should be displayed in results?

20 Enter number between 1 and 50

How many miles radius should be searched?

10 Enter number between 1 and 50

Enter some PNC Branch infoCost Center:

Company #AddressCity State Zip

Bank Number:

Select a PNC Branch

Enter some Competitive Branch Info

Parent Bank Name Drop list

AddressCity State ZipSelect a Competitor Branch

Search Start Over

Data Entry Sample – Text Boxes

Branch Manager Selector ToolSearch Specifications Results

Cost Center / Bank:NoAddressCity State Zip

PNC Branch Deposit Growth Deposits Market Share

2007 2006 2005 2007 2006 2005 2007 2006 20057% 3%

Bank Name Distance (mi) Address City State Zip Deposit Growth Deposits Market Share2007 2006 2005 2007 2006 2005 2007 2006 2005

Print All Print SelectedChange Search

Denovo? HQ

Export All Export Selected

Components of a Form

Objects Hold and display information

Events Activities that trigger code procedures to run

Code General declarations and Procedures

Types of Procedures

Event Procedures Run when a particular event occurs “Attached” to a particular object

Subroutines Available to any code procedure via CALL

Functions Available to any code procedure

Form Events Several, but here are the common ones:

Load – occurs when Form is requested Activate – occurs when Form is being

displayed in preparation for starting GotFocus – occurs when Form is displayed

and ready for user interaction LostFocus – occurs when user is done with

Form Deactivate – occurs when Form is closing Unload – occurs when Form is being removed

Event Procedure Same structure as subroutines Name is object_event

Ex: Sub Form_Load() Starts with Scope

Public or Private Private by default

Means only available to form Some subroutines and functions you write can

be Public Available to any form or procedure in entire

application

Form Event Procedure ExamplePrivate Sub Form_Load()

Dim boolFlag As BooleanDim intCount As IntegerDim strFilter As String

If strFilter <> "" Then:

End IfEnd Sub

Form Objects

Plenty, but the ones we’ll be working with: Text box Label – Text Command button List box Combo box – List box plus text box Checkbox – True/False Option button – Select one of a group

Object Elements

Properties Attributes of object Ex: Caption (“label” on command button) Properties can have properties

Ex: Font in text box Size, type, bold, etc

Events Event Code

Object Properties

Referenced with dot notation Ex: CommandOK.Caption = “OK” Ex: Text1.Font.Size = 16

Can be referenced or changed by any procedure in Form

Different objects have different properties Full list of object’s properties can be seen in

the Visual Basic Developer Studio

Message Box

Remember when I said Form was “primary” means of communicating with user?

Message Box is other Two forms:

MsgBox – Message to user (one-way) InputBox – Ask for data from user (two-way)

Both forms are created with a function

MsgBox function

Causes a small popup window to appear in the middle of the screen

Has OK button for user to click to remove popup

MsgBox(<text>) Example:

MsgBox(“Error! Wrong Data Type”)

InputBox function Causes popup window to appear in middle of

screen Contains a text box and OK button Text parameter clues user into what to enter User enters text and clicks OK Function returns the text in text box Example:

DIM Response As StringResponse = InputBox(“Enter number of

students”)

DoCmd object

Performs actions that trigger events Usually used to perform Form level actions

Like opening and closing forms Can be used in any procedure Example:

DoCmd.OpenForm “GetData”