CSI 101 Elements of Computing – Spring 2009 Lecture #11 – Structures of Visual Basic Wednesday, 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 Tool bar Status bar Contains words Produces dropdown menus Tool bar Contains icons Status bar Bottom Contains messages or other information

Example of Parts of a Form Note you can have more than one tool bar. There is only one Title bar, menu bar, and status bar, however.

Types of Forms Splash page Main Menu (Switchboard) Data Entry 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 This one takes the same philosophy as a menu bar, but has better labels

Submenu – Simple Example Obtained by clicking on the Inventory button from the form on Slide 7

Search Specifications Branch Manager Selector Tool Search Specifications Results Which best describes selection requirements? Enter some PNC Branch info º Find competitor branches near PNC branch Cost Center: Bank Number: º Find branches near specific competitor Company # Should headquarters be included in search results? Address º No (default) City State Zip º Yes Select a PNC Branch What about Denovo competitive branches? º Exclude (default) Include º º Only show Denovo Enter some Competitive Branch Info How many branches should be displayed in results? Parent Bank Name Drop list 20 Enter number between 1 and 50 Address This is a sample of data interactive screen. There are option buttons, text boxes, and command buttons. Go over each. City State Zip How many miles radius should be searched? Select a Competitor Branch 10 Enter number between 1 and 50 Search Start Over

Data Entry Sample – Text Boxes

Search Specifications Branch Manager Selector Tool Search Specifications Results Cost Center / Bank:No Address PNC Branch City State Zip Deposit Growth Deposits Market Share 2007 2006 2005 2007 2006 2005 2007 2006 2005 7% 3% Deposit Growth Deposits Market Share Denovo? HQ Bank Name Distance (mi) Address City State Zip 2007 2006 2005 2007 2006 2005 2007 2006 2005 Change Search Export All Export Selected Print All Print Selected

Components of a Form Objects Events Code Hold and display information Activities that trigger code procedures to run Code General declarations and Procedures

Types of Procedures Event Procedures Subroutines Functions 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 Example Private Sub Form_Load() Dim boolFlag As Boolean Dim intCount As Integer Dim strFilter As String If strFilter <> "" Then : End If End 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 Events Event Code 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 I’ll go over using the Developer Studio in the next lecture

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 String Response = 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”