objectives - furman universitycs.furman.edu/~pbatchelor/csc105/myppt/vba continued...10/22/2013 12...

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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.

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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.


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Using the VB Editor


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The VB Editor for an Excel Workbook

Menu bar and toolbar

Properties window used 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.


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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.


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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.


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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


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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


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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


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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.


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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 application


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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.


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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


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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.


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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.


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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.


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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 ( ).


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Format Output Results

• Use Format function to

format results of

calculations.

• Uses predefined formats

to change the appearance

of text.

• Examples:

– Currency

– Decimal

– Percent


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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.


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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.


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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.


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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


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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.

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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.

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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


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objectives - furman universitycs.furman.edu/~pbatchelor/csc105/myppt/vba continued...10/22/2013 12...

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