objectives understand the software development lifecycle perform calculations use decision...

Objectives

• Understand the software development lifecycle

• Perform calculations• Use decision structures• Perform data validation• Use logical operators• Use the For...Next loop statement• Use the Do...Loop statement

Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall.

Launching the VBA Interface

• To launch the VB Editor in your application:

• Click the File tab, click Options, click Customize Ribbon, click the Developer check box in the Main Tabs list, and then click OK.


Using the VB Editor


The VB Editor for an Excel Workbook

Menu bar and toolbar

Properties windowused to set

properties for objects.

Code Window

The Project Explorer lists the Workbook name

Project Explorer

• The left side of the VB Editor contains the Project Explorer, which is similar to the Windows Explorer.

• A project is a collection of modules and objects needed to run an application.

• A module is a container to organize programming code.


Properties Window

• The Properties window displays the properties or attributes for the currently selected object in the Project Explorer.

• The Properties window is used to set properties for an object that you can change or set a value.


Code Window• The Code window is a text editor for writing and

editing VBA programming statements.• You enter your code statements in design time. • VBA executes the procedure in run time.• A procedure is a named sequence of programming

statements that performs a set of actions. – Programming statements include: procedures, variable

and constant declarations, and mathematical expressions. – When you create several macros in a workbook, Excel

stores each macro as a procedure in one module. – The name you enter when you record a macro becomes

the name of an individual procedure in VBA.


Identify Code in the Code Window

• Procedure name• A procedure is a

named sequence of programming statements that performs a set of actions. Programming statements include: procedures, variable and constant declarations, and mathematical expressions. Comments

• Keywords - text or a symbol used for a specific purpose in a programming language

• Indented VBA statements


Creating Procedures• An event is an action, such as the

user clicking a button at run time that triggers a program instruction

• A sub procedure is a procedure that performs an action but does not return a specific value, such as:Sub Display_Message () Indented VBA statements

End Sub• A function procedure performs an

action and returns a value. • A property procedure creates or

manipulates a custom property. • A public procedure is available to

any object in the application. • A private procedure is available

only to a specific object or module


Getting Help and Debugging Errors

• Use Help to learn more about VBA.

• Explanation of terminology• Examples of programming code• For specific context assistance,

click on a keyword, such as Sub, and then press F1.

• The Debug menu helps you identify errors in programming code


Declaring and Using Variables

• Variables are programmer-defined names.

• Variables can store values that can change while the application is running.

• Variables store values in computer memory.

• A program code statement can change the value at any time.

• A value for a variable exists only while a program is running.


Declaring and Using Constants

• Constants store values that are specified at design time.

• Constants remain the same while the application is running.

• Programmers can change a constant’s value at design time.

• Types of constants include:– Intrinsic—specific to an application– User-defined—created by a programmer– Conditional compiler—defined in the host

applicationCopyright © 2012 Pearson Education, Inc. Publishing as Prentice

Hall.

Select a Data Type

• All variables and constants have a data type.

• The data type refers to the type of data the variable or constant can hold.

• The data type defines how the data is stored in the computer’s memory.


Select a Data Type (Cont.)• Common VBA data types include:–Decimal—Value that contains decimal

numbers scaled by a power of 10–Double—Double-precision floating-point

numbers with 14 digits of accuracy– Integer—Whole numbers, no decimal

points or places behind the decimal– String—Alphanumeric data including

letters, numbers, spaces, punctuation, and other characters with a fixed length


Declaring Variables and Assigning Values

• The declaration (Dim) statement assigns: – Name – Data type– Allocates memory to store a

value for the variable or constant

• Variables named with the Public prefix can be used by all procedures.

• The Scope specifies which statements can access a variable or constant.Copyright © 2012 Pearson Education, Inc. Publishing as Prentice

Hall.

Creating an Input Box• To obtain data from the user,

create an input box.• The InputBox function

(InputBox) prompts the user to enter a value.

• The MessageBox function displays the resulting message.

• Concatenate is the process of joining two or more text strings. Use the ampersand character (&) or plus sign (+) to concatenate, or join, two values, such as MsgBox "Last Name is: " & strLastName shown in this example.


Convert Strings to Numeric Values

• User input using the InputBox function is returned to the procedure as a text string by default.

• Data for calculations must be converted to numeric data by using the Val Function.


Performing Calculations

• Create arithmetic expressions using variables and mathematical operators.

• Order of precedence is the order arithmetic expressions are performed.

• Combine multiple operations with parentheses ( ).


Format Output Results

• Use Format function to format results of calculations.

• Uses predefined formats to change the appearance of text.

• Examples:– Currency– Decimal– Percent


Common Programming Structures

• Sequence structures execute statements in the order they appear.

• Decision structures make comparisons between values, variables, and/or constants and then execute statements based on the comparison.

• Repetition structures repeat the execution of a series of statements at run time.


Using Decision Structures• If…Then

statements represent the simplest type of decision structure.

• If…Then…Else statements test for a condition and specify one option if the test evaluates to True and another if it evaluates to False.


Create a Select Case Statement

• The Select Case statement compares an expression or a value to a set of cases, situations, or ranges.

• A case is an individual condition to test.


Repetition Structures

• Repetition structures complete an operation a specific number of times.

• Generally while a certain condition is true or until a condition tests true

• Two common repetition structures– For…Next loop– Do…Loop


Using the For…Next Loop Statement

• The For…Next statement repeats:– Loop—set of

statements or a procedure

– A specific number of times

• The counter keeps track of the number of iterations through the loop.

• The step value is the number the counter is incremented or decremented during each iteration of the loop.

Using the Do…Loop Statement• A Do…Loop

statement executes a block of statements while:– A condition

remains true– Or until a

condition is true

• Can be written with a pretest or posttest loop

• A pretest performs the logical test first and executes the code within the loop if the test is true.

• A posttest executes the code within the loop one time and then performs the logical test to determine if the loop iterates again.

Loop Until a Condition Becomes True

• Do Until loop repeats the iterations of the loop until the specified condition evaluates to True.

• Can be written with a pretest or posttest loop


objectives understand the software development lifecycle perform calculations use decision...

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