Review for Quiz_1

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Microsoft Visual Basic 2010: Reloaded, Fourth Edition 1

Visual Basic -1 Quiz #1 Review

OOP Terminology

OOP: Object-oriented programming

Class: blueprint used to create an object

Object:

Represents a real-world entity

Attributes (or properties): describe the object

Methods: behaviors or operations the object can

perform


OOP Terminology

(continued) Object-oriented program: one that focuses on

objects the program can use to accomplish its goal

Integrates processes and data into objects

Procedure-oriented program: one that focuses on individual tasks and their sequence


Visual Studio 2010

Integrated Development Environment (IDE):

Contains all the tools and features needed to create,

run, and test programs

Includes an editor and compiler

Visual Studio 2010:

IDE used to create Windows or Web-based programs

Includes Visual Basic 2010, Visual C++ 2010, &Visual

C# 2010, etc


Visual Studio 2010 (continued)

Application: program or suite of programs

Windows-based application:

Has a Windows user interface

Runs on a desktop computer

Web-based application:

Has a Web user interface

Runs on a server

Use a computer browser to access it

User interface: what the user sees and interacts with

when using an application

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The Properties Window

Properties window: displays properties of selected object

Default property values are assigned when an object is created

Properties list:

Left column displays names of properties

Settings box: Right column containing the current value of each property


The Me.Close Method

Me.Close method: closes the current form

Method: predefined VB procedure that can be

invoked (called)


IDE Windows

Toolbox: contains tools for creating the GUI (Controls)

Form control: acts as a container for other controls

Label control: contains text that a user cannot edit

Button control: performs an immediate action when clicked

Container controls: - Binds other controls visually and programmatically

Group Box Has Text Caption

Panel No Text Caption

Table Layout Panel Holds other controls in a table format of Rows and Columns


Planning an Application

Plan the application before creating the user interface

Work jointly with the user

Define the tasks that need to be performed

Get copies of any currently used manual forms

Identify the Tasks your application must perform

Identify Objects which you will assign to the tasks

Identify the triggering Events

Make a TOE (Task, Object, Event) chart:

Shows applications tasks, objects, and events

Design the user interface

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Identifying the Applications Tasks

(continued)

First, review current user procedures and forms

Steps:

Identify the desired outputs and necessary inputs

Identify the processing needed to change the inputs

into the outputs

Identify the need to clear the screen between

transactions

Identify how the user will end the application


Identifying the Objects

Assign each task to an object in the TOE

TextBox tool: instantiates a text box control

TextBox:

Used to allow the user to input information

Use Labels to guide the user

Use Buttons to initiate the calculations

Generate Events


Identifying the Events

Text boxes: no special events needed for user to

enter the text (None that you have to code)

Labels: no special events needed to display the

prompts (None that you have to code)

Buttons:

Action must occur when each button is clicked

(Click Event) (You have to code these)


TOE Chart

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Designing the User Interface

Follow Windows standards for:

Consistency

Ease of use

Familiar look and feel

Primary window:

The main window in an application

Dialog boxes: windows used to support and

supplement a users activities in the primary window


Designing the User Interface

(continued)

Primary Windows (MainForm)

Can be resized, minimized, maximized, and closed

by the user

Title Bar includes:

Minimize, Maximize, and Close buttons on the right

Control menu on the left

Dialog Boxes

Can be closed only

Title Bar includes:

Close button and optionally a Help button

No control menu


Arranging the Controls

Guidelines:

Information should flow either vertically or

horizontally

Group related controls together using white space or

container controls

Container controls:

GroupBox control

Panel control

TableLayoutPanel control


Arranging the Controls (continued)

Control Guidelines:

Use a label with each text box

Left-align the labels text (I prefer Right-align)

Position label to left of or above the text box it

identifies (I prefer to the left)

Labels and button captions should be 1 to 3 words only,

and appear on one line

Labels and captions should be meaningful

Use sentence capitalization for labels

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Including Graphics and Fonts

in the User Interface

Graphics Guidelines:

Human eye is drawn to pictures before text

Include graphics only if necessary

Use for aesthetic purposes

Use to clarify a portion of the screen

Font Guidelines:

Use only one font type for the text in a form

12-point font is easiest to read at high screen resolution

Avoid italics and underlining

Use bold only for titles, headings, and key terms


Including Color in the User Interface

Human eye is drawn to color before B&W

Color Guidelines:

Use color sparingly

Some people have trouble distinguishing colors

What is acceptable in colors is subjective

Color may have specific meaning in certain cultures

Use black or dark text on a white or light background

Use maximum of 3 different colors that complement each other

Do not use color as the only means of identification


Assigning Access Keys

Access key:

Allows user to select an object using Alt + access key

Appears underlined on the button caption

Is not case-sensitive

Include & in front of the character to be used as the access key:

&Calculate Order Calculate Order

Access Key Guidelines:

Assign access keys to each control that can accept user

input


Assigning Access Keys (continued)

Advantages of using access keys:

User does not need mouse to navigate and activate controls

Allows fast typists to keep hands on keyboard

Facilitates use of the application by people with disabilities

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Setting the TabIndex Property

TabIndex property:

Determines the order in which a control receives the

focus when the Tab key is pressed

Starts at 0

Default TabIndex values are set according to the order

in which the controls were added to the form

When a form starts, the control with the lowest

TabIndex value gets Focus unless Focus is forced to

some other control by the code.

Focus: the state of being able to accept user input


User Interface Summary

Align controls to flow horizontally or vertically

Group related controls visually with white space or

container controls, and maintain consistent margins

Use meaningful labels and captions of 1-3 words

Use graphics and colors sparingly

Use TabIndex property to control where the focus

goes when Tab key is used

BE CONSISTANT

Microsoft Visual Basic 2010: Reloaded, Fourth Edition 23 Microsoft Visual Basic 2010: Reloaded, 23

Chapter 3

Variables

Variables: computer memory locations used to store data (objects) while an application is running

Every variable has a:

Name

Data type

Scope

Lifetime

Microsoft Visual Basic 2010: Reloaded, Fourth Edition 24 Microsoft Visual Basic 24

Selecting a Data Type for a Variable

Each variable must be assigned a data type

Data type: the type of data the variable can store

Each data type is a CLASS

A group of instructions used to create an object

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Selecting a Name for a Variable

(continued)


Declaring a Variable

Declaration statement: used to declare, or create,

a variable

Declaration statement includes

Scope keyword: Dim or Private or Static

Public

Scope determines Lifetime

Name of the variable

Data type

Initial value (optional)


Initializing a Variables

Variables are initialized when they are Instantiated

If you do not provide a value, VB does it for you

VB sets a default value based on data type

Numeric types normally initialized to 0 (zero)

String types set to nothing

If your code expects variables to be initialized to a

particular value (even if 0) set it yourself in the

declaration


Assigning Data to an Existing

Variable

Assignment statement:

Used to assign values to properties of controls

Used to assign values to variables

Assignment operator: (=)

Value on the right of the = operator is assigned to the

variable on the left of the = operator

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Variable (continued)

String: group of characters enclosed in quotation

marks

Literal constant:

An item of data whose value does not change while the

application is running

Can be a numeric or a string literal constant

A numeric literal with a decimal place is treated as a

Double type. (eg .03)

Literal type character: forces a literal constant to

assume a specific data type (Always use it)





Using the TryParse Method

Method: a specific portion of a classs instructions that performs a task for the class

TryParse method:

Part of every numeric data types class

Used to convert a string to that numeric data type

TryParse method has either 2 or 4 arguments

String: string value to be converted

NumberStyles (optional): allows formatting characters to be in the data to be converted

IFormatProvider (optional): specifies formatting

Variable: location to store the result


Using the TryParse Method

(continued) Assign the TryParse methods return value to a UNIQUE

Boolean variable. (Data Validation)

If True, the conversion was successful

If False, the value could not be converted

Must have an Imports statement in the General Declarations section of code to use NumberStyles and

NumberformatInfo.CurrentInfo:

Imports System.Globalization

Line continuation character: the underscore (_)

Breaks up a long instruction into two or more lines

Must appear at end of line, preceded by a space

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Using the Convert Class

Convert class:

Contains methods for converting numeric values to

specific data types

Use the dot member access operator to separate

the class name from the method name


Writing Arithmetic Expressions



(continued) Precedence number: indicates the order in which

an operation in an expression is performed

If an expression has two operators with the same

precedence, they are evaluated from left to right

Use parentheses to change the order of evaluation

Consider not relying on precedence and always

use parentheses (precedence rules vary)



(continued)

Using Parentheses

Should be equal number of open ( and closed )

parentheses in an expression

Write your expression by hand before you code it

Make it part of your Pseudocode

Check your parentheses

Count the # of opens and closes

Evaluate your expression from the inside out

If its too complicated, break up your expression into

multiple expressions, use intermediate variables

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The Scope and Lifetime of a

Variable

Scope: indicates where the variable can be used

Lifetime: indicates how long the variable remains in

memory

Variables are usually declared in one of two places:

Within a procedure

In the forms Declarations section

Procedure-level variable: declared within a

procedure

Procedure scope: only the procedure can use the

variable


The Scope and Lifetime of a


With procedure-level scope, two procedures can

each use the same variable names

Class scope: variable can be used by all procedures in the form

Class-level variable:

Declared in the forms Declarations section

Use Private keyword in declaration

Class-level variables retain their values until the application ends


Static Variables

Static variable:

Procedure-level variable that retains its value even after the procedure ends

Retains its value until the application ends

Can be used instead of a Class-level variable

A static variable has:

Same lifetime as a Class-level variable

Narrower scope than a Class-level variable

Declared using the Static keyword


Setting the Focus

Focus method: moves the focus to a specified

control at runtime.

Most form controls have a Focus method.

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Setting the Focus

(continued)


Important Concepts About

Variables and Constants

Variables and named constants are memory

locations that store data

Variables can change value at Runtime, but

constants cannot

Variables and constants have a name, data type,

scope, and lifetime

Use Dim to declare a variable at block or

procedure level

Use Private to declare a variable at Class level


Important Concepts About

Variables and Constants

(continued)

Assignment statement is used to assign values to an existing variable

Assignment Operator is the = sign

Literals are constant items of data

Use the TryParse method to convert a user entered string to

a number

Use the Imports statement to import a namespace

The Convert class contains methods to convert values to a

specified data type. Use to convert datatypes within a

program


Additional Concepts About

Variables

A procedure-level variable is usable only by the

procedure in which it is declared

A Class-level variable is usable by all procedures

in the form

A block-level variable is usable only within the

block in which it is declared

A static variable is a procedure-level variable that

retains its value when the procedure ends

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Microsoft Visual Basic 2010: Reloaded, Fourth Edition 45 Microsoft Visual Basic 2005: Reloaded, Second Edition 45

Miscellaneous Concepts

Option Explicit On forces declaration of all

variables before use

Option Strict On disallows any implicit type

conversions that may cause a loss of data

Option Infer Off statement: ensures that every

variable is declared with a data type

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Review for Quiz_1