VBA - Quick Guide

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VBA - Overview

VBA stands for Visual Basic for Applications an event-driven programming language from Microsoft that is now predominantly used with Microsoft office applications such as MSExcel, MS-Word, and MS-Access.

It helps techies to build customized applications and solutions to enhance the capabilities of those applications. The advantage of this facility is that you NEED NOT have visual basic installed on our PC, however, installing Office will implicitly help in achieving the purpose.

You can use VBA in all office versions, right from MS-Office 97 to MS-Office 2013 and also with any of the latest versions available. Among VBA, Excel VBA is the most popular. The advantage of using VBA is that you can build very powerful tools in MS Excel using linear programming.

Application of VBA

You might wonder why to use VBA in Excel as MS-Excel itself provides loads of inbuilt functions. MS-Excel provides only basic inbuilt functions which might not be sufficient to perform complex calculations. Under such circumstances, VBA becomes the most obvious solution.

For example, it is very hard to calculate the monthly repayment of a loan using Excel's built-in formulas. Rather, it is easy to program a VBA for such a calculation.

Accessing VBA Editor

In Excel window, press "ALT+F11". A VBA window opens up as shown in the following screenshot.

VBA - Excel Macros

In this chapter, you will learn how to write a simple macro in a step by step manner.

Step 1 − First, enable 'Developer' menu in Excel 20XX. To do the same, click File → Options.

Step 2 − Click ‘Customize the Ribbon’ tab and check 'Developer'. Click 'OK'.

Step 3 − The 'Developer' ribbon appears in the menu bar.

Step 4 − Click the 'Visual Basic' button to open the VBA Editor.

Step 5 − Start scripting by adding a button. Click Insert → Select the button.

Step 6 − Perform a right-click and choose 'properties'.

Step 7 − Edit the name and caption as shown in the following screenshot.

Step 8 − Now double-click the button and the sub-procedure outline will be displayed as shown in the following screenshot.

Step 9 − Start coding by simply adding a message.

Private Sub say_helloworld_Click()
   MsgBox "Hi"
End Sub

Step 10 − Click the button to execute the sub-procedure. The output of the sub-procedure is shown in the following screenshot. Make sure that you do have design mode turned on. Simply click it to turn it on if it is not on.

Note − In further chapters, we will demonstrate using a simple button, as explained from step#1 to 10. Hence , it is important to understand this chapter thoroughly.

VBA - Excel Terms

In this chapter, you will acquaint yourself with the commonly used excel VBA terminologies. These terminologies will be used in further modules, hence understanding each one of these is important.

Modules

Modules is the area where the code is written. This is a new Workbook, hence there aren't any Modules.

To insert a Module, navigate to Insert → Module. Once a module is inserted 'module1' is created.

Within the modules, we can write VBA code and the code is written within a Procedure. A Procedure/Sub Procedure is a series of VBA statements instructing what to do.

Procedure

Procedures are a group of statements executed as a whole, which instructs Excel how to perform a specific task. The task performed can be a very simple or a very complicated task. However, it is a good practice to break down complicated procedures into smaller ones.

The two main types of Procedures are Sub and Function.

Function

A function is a group of reusable code, which can be called anywhere in your program. This eliminates the need of writing the same code over and over again. This helps the programmers to divide a big program into a number of small and manageable functions.

Apart from inbuilt Functions, VBA allows to write user-defined functions as well and statements are written between Function and End Function.

Sub-Procedures

Sub-procedures work similar to functions. While sub procedures DO NOT Return a value, functions may or may not return a value. Sub procedures CAN be called without call keyword. Sub procedures are always enclosed within Sub and End Sub statements.

VBA - Macro Comments

Comments are used to document the program logic and the user information with which other programmers can seamlessly work on the same code in future.

It includes information such as developed by, modified by, and can also include incorporated logic. Comments are ignored by the interpreter while execution.

Comments in VBA are denoted by two methods.

• Any statement that starts with a Single Quote (') is treated as comment. Following is an example.

' This Script is invoked after successful login 
' Written by : TutorialsPoint 
' Return Value : True / False

• Any statement that starts with the keyword "REM". Following is an example.

REM This Script is written to Validate the Entered Input 
REM Modified by  : Tutorials point/user2

VBA - Message Box

The MsgBox function displays a message box and waits for the user to click a button and then an action is performed based on the button clicked by the user.

Syntax

MsgBox(prompt[,buttons][,title][,helpfile,context])

Parameter Description

• Prompt − A Required Parameter. A String that is displayed as a message in the dialog box. The maximum length of prompt is approximately 1024 characters. If the message extends to more than a line, then the lines can be separated using a carriage return character (Chr(13)) or a linefeed character (Chr(10)) between each line.

• Buttons − An Optional Parameter. A Numeric expression that specifies the type of buttons to display, the icon style to use, the identity of the default button, and the modality of the message box. If left blank, the default value for buttons is 0.

• Title − An Optional Parameter. A String expression displayed in the title bar of the dialog box. If the title is left blank, the application name is placed in the title bar.

• Helpfile − An Optional Parameter. A String expression that identifies the Help file to use for providing context-sensitive help for the dialog box.

• Context − An Optional Parameter. A Numeric expression that identifies the Help context number assigned by the Help author to the appropriate Help topic. If context is provided, helpfile must also be provided.

The Buttons parameter can take any of the following values −

• 0 vbOKOnly - Displays OK button only.

• 1 vbOKCancel - Displays OK and Cancel buttons.

• 2 vbAbortRetryIgnore - Displays Abort, Retry, and Ignore buttons.

• 3 vbYesNoCancel - Displays Yes, No, and Cancel buttons.

• 4 vbYesNo - Displays Yes and No buttons.

• 5 vbRetryCancel - Displays Retry and Cancel buttons.

• 16 vbCritical - Displays Critical Message icon.

• 32 vbQuestion - Displays Warning Query icon.

• 48 vbExclamation - Displays Warning Message icon.

• 64 vbInformation - Displays Information Message icon.

• 0 vbDefaultButton1 - First button is default.

• 256 vbDefaultButton2 - Second button is default.

• 512 vbDefaultButton3 - Third button is default.

• 768 vbDefaultButton4 - Fourth button is default.

• 0 vbApplicationModal Application modal - The current application will not work until the user responds to the message box.

• 4096 vbSystemModal System modal - All applications will not work until the user responds to the message box.

The above values are logically divided into four groups: The first group (0 to 5) indicates the buttons to be displayed in the message box. The second group (16, 32, 48, 64) describes the style of the icon to be displayed, the third group (0, 256, 512, 768) indicates which button must be the default, and the fourth group (0, 4096) determines the modality of the message box.

Return Values

The MsgBox function can return one of the following values which can be used to identify the button the user has clicked in the message box.

• 1 - vbOK - OK was clicked
• 2 - vbCancel - Cancel was clicked
• 3 - vbAbort - Abort was clicked
• 4 - vbRetry - Retry was clicked
• 5 - vbIgnore - Ignore was clicked
• 6 - vbYes - Yes was clicked
• 7 - vbNo - No was clicked

Example

Function MessageBox_Demo() 
   'Message Box with just prompt message 
   MsgBox("Welcome")     
   
   'Message Box with title, yes no and cancel Butttons  
   int a = MsgBox("Do you like blue color?",3,"Choose options") 
   ' Assume that you press No Button  
   msgbox ("The Value of a is " & a) 
End Function

Output

Step 1 − The above Function can be executed either by clicking the "Run" button on VBA Window or by calling the function from Excel Worksheet as shown in the following screenshot.

Step 2 − A Simple Message box is displayed with a message "Welcome" and an "OK" Button

Step 3 − After Clicking OK, yet another dialog box is displayed with a message along with "yes, no, and cancel" buttons.

Step 4 − After clicking the ‘No’ button, the value of that button (7) is stored as an integer and displayed as a message box to the user as shown in the following screenshot. Using this value, it can be understood which button the user has clicked.

VBA - InputBox

The InputBox function prompts the users to enter values. After entering the values, if the user clicks the OK button or presses ENTER on the keyboard, the InputBox function will return the text in the text box. If the user clicks the Cancel button, the function will return an empty string ("").

Syntax

InputBox(prompt[,title][,default][,xpos][,ypos][,helpfile,context])

Parameter Description

• Prompt − A required parameter. A String that is displayed as a message in the dialog box. The maximum length of prompt is approximately 1024 characters. If the message extends to more than a line, then the lines can be separated using a carriage return character (Chr(13)) or a linefeed character (Chr(10)) between each line.

• Title − An optional parameter. A String expression displayed in the title bar of the dialog box. If the title is left blank, the application name is placed in the title bar.

• Default − An optional parameter. A default text in the text box that the user would like to be displayed.

• XPos − An optional parameter. The position of X axis represents the prompt distance from the left side of the screen horizontally. If left blank, the input box is horizontally centered.

• YPos − An optional parameter. The position of Y axis represents the prompt distance from the left side of the screen vertically. If left blank, the input box is vertically centered.

• Helpfile − An optional parameter. A String expression that identifies the helpfile to be used to provide context-sensitive Help for the dialog box.

• context − An optional parameter. A Numeric expression that identifies the Help context number assigned by the Help author to the appropriate Help topic. If context is provided, helpfile must also be provided.

Example

Let us calculate the area of a rectangle by getting values from the user at run time with the help of two input boxes (one for length and one for width).

Function findArea() 
   Dim Length As Double 
   Dim Width As Double 
   
   Length = InputBox("Enter Length ", "Enter a Number") 
   Width = InputBox("Enter Width", "Enter a Number") 
   findArea = Length * Width 
End Function

Output

Step 1 − To execute the same, call using the function name and press Enter as shown in the following screenshot.

Step 2 − Upon execution, the First input box (length) is displayed. Enter a value into the input box.

Step 3 − After entering the first value, the second input box (width) is displayed.

Step 4 − Upon entering the second number, click the OK button. The area is displayed as shown in the following screenshot.

VBA - Variables

Variable is a named memory location used to hold a value that can be changed during the script execution. Following are the basic rules for naming a variable.

• You must use a letter as the first character.

• You can't use a space, period (.), exclamation mark (!), or the characters @, &, $, # in the name.

• Name can't exceed 255 characters in length.

• You cannot use Visual Basic reserved keywords as variable name.

Syntax

In VBA, you need to declare the variables before using them.

Dim <<variable_name>> As <<variable_type>>

Data Types

There are many VBA data types, which can be divided into two main categories, namely numeric and non-numeric data types.

Numeric Data Types

Following table displays the numeric data types and the allowed range of values.

Non-Numeric Data Types

Following table displays the non-numeric data types and the allowed range of values.

Example

Let us create a button and name it as 'Variables_demo' to demonstrate the use of variables.

Private Sub say_helloworld_Click()
   Dim password As String
   password = "Admin#1"

   Dim num As Integer
   num = 1234

   Dim BirthDay As Date
   BirthDay = DateValue("30 / 10 / 2020")

   MsgBox "Passowrd is " & password & Chr(10) & "Value of num is " &
      num & Chr(10) & "Value of Birthday is " & BirthDay
End Sub

Output

Upon executing the script, the output will be as shown in the following screenshot.

VBA - Constants

Constant is a named memory location used to hold a value that CANNOT be changed during the script execution. If a user tries to change a Constant value, the script execution ends up with an error. Constants are declared the same way the variables are declared.

Following are the rules for naming a constant.

• You must use a letter as the first character.

• You can't use a space, period (.), exclamation mark (!), or the characters @, &, $, # in the name.

• Name can't exceed 255 characters in length.

• You cannot use Visual Basic reserved keywords as variable name.

Syntax

In VBA, we need to assign a value to the declared Constants. An error is thrown, if we try to change the value of the constant.

Const <<constant_name>> As <<constant_type>> = <<constant_value>>

Example

Let us create a button "Constant_demo" to demonstrate how to work with constants.

Private Sub Constant_demo_Click() 
   Const MyInteger As Integer = 42 
   Const myDate As Date = #2/2/2020# 
   Const myDay As String = "Sunday" 
   
   MsgBox "Integer is " & MyInteger & Chr(10) & "myDate is " 
      & myDate & Chr(10) & "myDay is " & myDay  
End Sub

Output

Upon executing the script, the output will be displayed as shown in the following screenshot.

VBA - Operators

An Operator can be defined using a simple expression - 4 + 5 is equal to 9. Here, 4 and 5 are called operands and + is called operator. VBA supports following types of operators −

• Arithmetic Operators
• Comparison Operators
• Logical (or Relational) Operators
• Concatenation Operators

The Arithmatic Operators

Following arithmetic operators are supported by VBA.

Assume variable A holds 5 and variable B holds 10, then −

Show Examples

The Comparison Operators

There are following comparison operators supported by VBA.

Assume variable A holds 10 and variable B holds 20, then −

Show Examples

The Logical Operators

Following logical operators are supported by VBA.

Assume variable A holds 10 and variable B holds 0, then −

Show Examples

The Concatenation Operators

Following Concatenation operators are supported by VBA.

Assume variable A holds 5 and variable B holds 10 then −

Show Examples

Assume variable A = "Microsoft" and variable B = "VBScript", then −

Note − Concatenation Operators can be used for both numbers and strings. The output depends on the context, if the variables hold numeric value or string value.

VBA - Decisions

Decision making allows the programmers to control the execution flow of a script or one of its sections. The execution is governed by one or more conditional statements.

Following is the general form of a typical decision making structure found in most of the programming languages.

VBA provides the following types of decision making statements. Click the following links to check their details.

VBA - Loops

There may be a situation when you need to execute a block of code several number of times. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on.

Programming languages provide various control structures that allow for more complicated execution paths.

A loop statement allows us to execute a statement or group of statements multiple times. Following is the general form of a loop statement in VBA.

VBA provides the following types of loops to handle looping requirements. Click the following links to check their detail.

Loop Control Statements

Loop control statements change execution from its normal sequence. When execution leaves a scope, all the remaining statements in the loop are NOT executed.

VBA supports the following control statements. Click the following links to check their detail.

VBA - Strings

Strings are a sequence of characters, which can consist of either alphabets, numbers, special characters, or all of them. A variable is said to be a string if it is enclosed within double quotes " ".

Syntax

variablename = "string"

Examples

str1 = "string"   ' Only Alphabets
str2 = "132.45"   ' Only Numbers
str3 = "!@#$;*"  ' Only Special Characters
Str4 = "Asc23@#"  ' Has all the above

String Functions

There are predefined VBA String functions, which help the developers to work with the strings very effectively. Following are String methods that are supported in VBA. Please click on each one of the methods to know in detail.

VBA - Date-Time Function

VBScript Date and Time Functions help the developers to convert date and time from one format to another or to express the date or time value in the format that suits a specific condition.

Date Functions

Time Functions

VBA - Arrays

We know very well that a variable is a container to store a value. Sometimes, developers are in a position to hold more than one value in a single variable at a time. When a series of values are stored in a single variable, then it is known as an array variable.

Array Declaration

Arrays are declared the same way a variable has been declared except that the declaration of an array variable uses parenthesis. In the following example, the size of the array is mentioned in the brackets.

'Method 1 : Using Dim
Dim arr1()	'Without Size

'Method 2 : Mentioning the Size
Dim arr2(5)  'Declared with size of 5

'Method 3 : using 'Array' Parameter
Dim arr3
arr3 = Array("apple","Orange","Grapes")

• Although, the array size is indicated as 5, it can hold 6 values as array index starts from ZERO.

• Array Index cannot be negative.

• VBScript Arrays can store any type of variable in an array. Hence, an array can store an integer, string, or characters in a single array variable.

Assigning Values to an Array

The values are assigned to the array by specifying an array index value against each one of the values to be assigned. It can be a string.

Example

Add a button and add the following function.

Private Sub Constant_demo_Click()
   Dim arr(5)
   arr(0) = "1"           'Number as String
   arr(1) = "VBScript"    'String
   arr(2) = 100 		     'Number
   arr(3) = 2.45 		     'Decimal Number
   arr(4) = #10/07/2013#  'Date
   arr(5) = #12.45 PM#    'Time
  
   msgbox("Value stored in Array index 0 : " & arr(0))
   msgbox("Value stored in Array index 1 : " & arr(1))
   msgbox("Value stored in Array index 2 : " & arr(2))
   msgbox("Value stored in Array index 3 : " & arr(3))
   msgbox("Value stored in Array index 4 : " & arr(4))
   msgbox("Value stored in Array index 5 : " & arr(5))
End Sub

When you execute the above function, it produces the following output.

Value stored in Array index 0 : 1
Value stored in Array index 1 : VBScript
Value stored in Array index 2 : 100
Value stored in Array index 3 : 2.45
Value stored in Array index 4 : 7/10/2013
Value stored in Array index 5 : 12:45:00 PM

Multi-Dimensional Arrays

Arrays are not just limited to a single dimension, however, they can have a maximum of 60 dimensions. Two-dimensional arrays are the most commonly used ones.

Example

In the following example, a multi-dimensional array is declared with 3 rows and 4 columns.

Private Sub Constant_demo_Click()
   Dim arr(2,3) as Variant	' Which has 3 rows and 4 columns
   arr(0,0) = "Apple" 
   arr(0,1) = "Orange"
   arr(0,2) = "Grapes"           
   arr(0,3) = "pineapple" 
   arr(1,0) = "cucumber"           
   arr(1,1) = "beans"           
   arr(1,2) = "carrot"           
   arr(1,3) = "tomato"           
   arr(2,0) = "potato"             
   arr(2,1) = "sandwitch"            
   arr(2,2) = "coffee"             
   arr(2,3) = "nuts"            
           
   msgbox("Value in Array index 0,1 : " &  arr(0,1))
   msgbox("Value in Array index 2,2 : " &  arr(2,2))
End Sub

When you execute the above function, it produces the following output.

Value stored in Array index : 0 , 1 : Orange
Value stored in Array index : 2 , 2 : coffee

ReDim Statement

ReDim statement is used to declare dynamic-array variables and allocate or reallocate storage space.

Syntax

ReDim [Preserve] varname(subscripts) [, varname(subscripts)]

Parameter Description

• Preserve − An optional parameter used to preserve the data in an existing array when you change the size of the last dimension.

• Varname − A required parameter, which denotes the name of the variable, which should follow the standard variable naming conventions.

• Subscripts − A required parameter, which indicates the size of the array.

Example

In the following example, an array has been redefined and then the values preserved when the existing size of the array is changed.

Note − Upon resizing an array smaller than it was originally, the data in the eliminated elements will be lost.

Private Sub Constant_demo_Click()
   Dim a() as variant
   i = 0
   redim a(5)
   a(0) = "XYZ"
   a(1) = 41.25
   a(2) = 22
  
   REDIM PRESERVE a(7)
   For i = 3 to 7
   a(i) = i
   Next
  
   'to Fetch the output
   For i = 0 to ubound(a)
      Msgbox a(i)
   Next
End Sub

When you execute the above function, it produces the following output.

XYZ
41.25
22
3
4
5
6
7

Array Methods

There are various inbuilt functions within VBScript which help the developers to handle arrays effectively. All the methods that are used in conjunction with arrays are listed below. Please click on the method name to know about it in detail.

VBA - User Defined Functions

A function is a group of reusable code which can be called anywhere in your program. This eliminates the need of writing the same code over and over again. This enables the programmers to divide a big program into a number of small and manageable functions.

Apart from inbuilt functions, VBA allows to write user-defined functions as well. In this chapter, you will learn how to write your own functions in VBA.

Function Definition

A VBA function can have an optional return statement. This is required if you want to return a value from a function.

For example, you can pass two numbers in a function and then you can expect from the function to return their multiplication in your calling program.

Note − A function can return multiple values separated by a comma as an array assigned to the function name itself.

Before we use a function, we need to define that particular function. The most common way to define a function in VBA is by using the Function keyword, followed by a unique function name and it may or may not carry a list of parameters and a statement with End Function keyword, which indicates the end of the function. Following is the basic syntax.

Syntax

Add a button and add the following function.

Function Functionname(parameter-list)
   statement 1
   statement 2
   statement 3
   .......
   statement n
End Function

Example

Add the following function which returns the area. Note that a value/values can be returned with the function name itself.

Function findArea(Length As Double, Optional Width As Variant)
   If IsMissing(Width) Then
      findArea = Length * Length
   Else
      findArea = Length * Width
   End If
End Function

Calling a Function

To invoke a function, call the function using the function name as shown in the following screenshot.

The output of the area as shown below will be displayed to the user.

VBA - Sub Procedure

Sub Procedures are similar to functions, however there are a few differences.

• Sub procedures DO NOT Return a value while functions may or may not return a value.

• Sub procedures CAN be called without a call keyword.

• Sub procedures are always enclosed within Sub and End Sub statements.

Example

Sub Area(x As Double, y As Double)
   MsgBox x * y
End Sub

Calling Procedures

To invoke a Procedure somewhere in the script, you can make a call from a function. We will not be able to use the same way as that of a function as sub procedure WILL NOT return a value.

Function findArea(Length As Double, Width As Variant)
   area Length, Width    ' To Calculate Area 'area' sub proc is called
End Function

Now you will be able to call the function only but not the sub procedure as shown in the following screenshot.

The area is calculated and shown only in the Message box.

The result cell displays ZERO as the area value is NOT returned from the function. In short, you cannot make a direct call to a sub procedure from the excel worksheet.

VBA - Events

VBA, an event-driven programming can be triggered when you change a cell or range of cell values manually. Change event may make things easier, but you can very quickly end a page full of formatting. There are two kinds of events.

• Worksheet Events
• Workbook Events

Worksheet Events

Worksheet Events are triggered when there is a change in the worksheet. It is created by performing a right-click on the sheet tab and choosing 'view code', and later pasting the code.

The user can select each one of those worksheets and choose "WorkSheet" from the drop down to get the list of all supported Worksheet events.

Following are the supported worksheet events that can be added by the user.

Private Sub Worksheet_Activate() 
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)    
Private Sub Worksheet_BeforeRightClick(ByVal Target As Range, Cancel As Boolean) 
Private Sub Worksheet_Calculate() 
Private Sub Worksheet_Change(ByVal Target As Range) 
Private Sub Worksheet_Deactivate() 
Private Sub Worksheet_FollowHyperlink(ByVal Target As Hyperlink) 
Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Example

Let us say, we just need to display a message before double click.

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
   MsgBox "Before Double Click"
End Sub

Output

Upon double-clicking on any cell, the message box is displayed to the user as shown in the following screenshot.

Workbook Events

Workbook events are triggered when there is a change in the workbook on the whole. We can add the code for workbook events by selecting the 'ThisWorkbook' and selecting 'workbook' from the dropdown as shown in the following screenshot. Immediately Workbook_open sub procedure is displayed to the user as seen in the following screenshot.

Following are the supported Workbook events that can be added by the user.

Private Sub Workbook_AddinUninstall() 
Private Sub Workbook_BeforeClose(Cancel As Boolean) 
Private Sub Workbook_BeforePrint(Cancel As Boolean) 
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean) 
Private Sub Workbook_Deactivate() 
Private Sub Workbook_NewSheet(ByVal Sh As Object) 
Private Sub Workbook_Open() 
Private Sub Workbook_SheetActivate(ByVal Sh As Object) 
Private Sub Workbook_SheetBeforeDoubleClick(ByVal Sh As Object, ByVal Target As Range, Cancel As Boolean) 
Private Sub Workbook_SheetBeforeRightClick(ByVal Sh As Object, ByVal Target As Range, Cancel As Boolean) 
Private Sub Workbook_SheetCalculate(ByVal Sh As Object) 
Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range) 
Private Sub Workbook_SheetDeactivate(ByVal Sh As Object) 
Private Sub Workbook_SheetFollowHyperlink(ByVal Sh As Object, ByVal Target As Hyperlink) 
Private Sub Workbook_SheetSelectionChange(ByVal Sh As Object, ByVal Target As Range) 
Private Sub Workbook_WindowActivate(ByVal Wn As Window) 
Private Sub Workbook_WindowDeactivate(ByVal Wn As Window) 
Private Sub Workbook_WindowResize(ByVal Wn As Window)

Example

Let us say, we just need to display a message to the user that a new sheet is created successfully, whenever a new sheet is created.

Private Sub Workbook_NewSheet(ByVal Sh As Object)
   MsgBox "New Sheet Created Successfully"
End Sub

Output

Upon creating a new excel sheet, a message is displayed to the user as shown in the following screenshot.

VBA - Error Handling

There are three types of errors in programming: (a) Syntax Errors, (b) Runtime Errors, and (c) Logical Errors.

Syntax errors

Syntax errors, also called as parsing errors, occur at the interpretation time for VBScript. For example, the following line causes a syntax error because it is missing a closing parenthesis.

Function ErrorHanlding_Demo()
   dim x,y
   x = "Tutorialspoint"
   y = Ucase(x
End Function

Runtime errors

Runtime errors, also called exceptions, occur during execution, after interpretation.

For example, the following line causes a runtime error because here the syntax is correct but at runtime it is trying to call fnmultiply, which is a non-existing function.

Function ErrorHanlding_Demo1()
   Dim x,y
   x = 10
   y = 20
   z = fnadd(x,y)
   a = fnmultiply(x,y)
End Function

Function fnadd(x,y)
   fnadd = x + y
End Function

Logical Errors

Logical errors can be the most difficult type of errors to track down. These errors are not the result of a syntax or runtime error. Instead, they occur when you make a mistake in the logic that drives your script and you do not get the result you expected.

You cannot catch those errors, because it depends on your business requirement what type of logic you want to put in your program.

For example, dividing a number by zero or a script that is written which enters into infinite loop.

Err Object

Assume if we have a runtime error, then the execution stops by displaying the error message. As a developer, if we want to capture the error, then Error Object is used.

Example

In the following example, Err.Number gives the error number and Err.Description gives the error description.

Err.Raise 6   ' Raise an overflow error.
MsgBox "Error # " & CStr(Err.Number) & " " & Err.Description
Err.Clear   ' Clear the error.

Error Handling

VBA enables an error-handling routine and can also be used to disable an error-handling routine. Without an On Error statement, any run-time error that occurs is fatal: an error message is displayed, and the execution stops abruptly.

On Error { GoTo [ line | 0 | -1 ] | Resume Next }

Example

Public Sub OnErrorDemo()
   On Error GoTo ErrorHandler   ' Enable error-handling routine.
   Dim x, y, z As Integer
   x = 50
   y = 0
   z = x / y   ' Divide by ZERO Error Raises
  
   ErrorHandler:    ' Error-handling routine.
   Select Case Err.Number   ' Evaluate error number.
      Case 10   ' Divide by zero error
         MsgBox ("You attempted to divide by zero!")
      Case Else
         MsgBox "UNKNOWN ERROR  - Error# " & Err.Number & " : " & Err.Description
   End Select
   Resume Next
End Sub

VBA - Excel Objects

When programming using VBA, there are few important objects that a user would be dealing with.

• Application Objects
• Workbook Objects
• Worksheet Objects
• Range Objects

Application Objects

The Application object consists of the following −

• Application-wide settings and options.
• Methods that return top-level objects, such as ActiveCell, ActiveSheet, and so on.

Example

'Example 1 :
Set xlapp = CreateObject("Excel.Sheet") 
xlapp.Application.Workbooks.Open "C:\test.xls"

'Example 2 :
Application.Windows("test.xls").Activate

'Example 3:
Application.ActiveCell.Font.Bold = True

Workbook Objects

The Workbook object is a member of the Workbooks collection and contains all the Workbook objects currently open in Microsoft Excel.

Example

'Ex 1 : To close Workbooks
Workbooks.Close

'Ex 2 : To Add an Empty Work Book
Workbooks.Add

'Ex 3: To Open a Workbook
Workbooks.Open FileName:="Test.xls", ReadOnly:=True

'Ex : 4 - To Activate WorkBooks
Workbooks("Test.xls").Worksheets("Sheet1").Activate

Worksheet Objects

The Worksheet object is a member of the Worksheets collection and contains all the Worksheet objects in a workbook.

Example

'Ex 1 : To make it Invisible
Worksheets(1).Visible = False

'Ex 2 : To protect an WorkSheet
Worksheets("Sheet1").Protect password:=strPassword, scenarios:=True

Range Objects

Range Objects represent a cell, a row, a column, or a selection of cells containing one or more continuous blocks of cells.

'Ex 1 : To Put a value in the cell A5
Worksheets("Sheet1").Range("A5").Value = "5235"

'Ex 2 : To put a value in range of Cells
Worksheets("Sheet1").Range("A1:A4").Value = 5

VBA - Text Files

You can also read Excel File and write the contents of the cell into a Text File using VBA. VBA allows the users to work with text files using two methods −

• File System Object
• using Write Command

File System Object (FSO)

As the name suggests, FSOs help the developers to work with drives, folders, and files. In this section, we will discuss how to use a FSO.

Drive

Drive is an object, which provides access to the properties of a particular disk drive or network share. Following properties are supported by Drive object −

• AvailableSpace
• DriveLetter
• DriveType
• FileSystem
• FreeSpace
• IsReady
• Path
• RootFolder
• SerialNumber
• ShareName
• TotalSize
• VolumeName

Example

Step 1 − Before proceeding to scripting using FSO, we should enable Microsoft Scripting Runtime. To do the same, navigate to Tools → References as shown in the following screenshot.

Step 2 − Add "Microsoft Scripting RunTime" and Click OK.

Step 3 − Add Data that you would like to write in a Text File and add a Command Button.

Step 4 − Now it is time to Script.

Private Sub fn_write_to_text_Click()
   Dim FilePath As String
   Dim CellData As String
   Dim LastCol As Long
   Dim LastRow As Long
  
   Dim fso As FileSystemObject
   Set fso = New FileSystemObject
   Dim stream As TextStream
  
   LastCol = ActiveSheet.UsedRange.Columns.Count
   LastRow = ActiveSheet.UsedRange.Rows.Count
    
   ' Create a TextStream.
   Set stream = fso.OpenTextFile("D:\Try\Support.log", ForWriting, True)
  
   CellData = ""
  
   For i = 1 To LastRow
      For j = 1 To LastCol
         CellData = Trim(ActiveCell(i, j).Value)
         stream.WriteLine "The Value at location (" & i & "," & j & ")" & CellData
      Next j
   Next i
  
   stream.Close
   MsgBox ("Job Done")
End Sub

Output

When executing the script, ensure that you place the cursor in the first cell of the worksheet. The Support.log file is created as shown in the following screenshot under "D:\Try".

The Contents of the file are shown in the following screenshot.

Write Command

Unlike FSO, we need NOT add any references, however, we will NOT be able to work with drives, files and folders. We will be able to just add the stream to the text file.

Example

Private Sub fn_write_to_text_Click()
   Dim FilePath As String
   Dim CellData As String
   Dim LastCol As Long
   Dim LastRow As Long
  
   LastCol = ActiveSheet.UsedRange.Columns.Count
   LastRow = ActiveSheet.UsedRange.Rows.Count
    
   FilePath = "D:\Try\write.txt"
   Open FilePath For Output As #2
  
   CellData = ""
   For i = 1 To LastRow
      For j = 1 To LastCol
         CellData = "The Value at location (" & i & "," & j & ")" & Trim(ActiveCell(i, j).Value)
         Write #2, CellData
      Next j
   Next i
  
   Close #2
   MsgBox ("Job Done")
End Sub

Output

Upon executing the script, the "write.txt" file is created in the location "D:\Try" as shown in the following screenshot.

The contents of the file are shown in the following screenshot.

VBA - Programming Charts

Using VBA, you can generate charts based on certain criteria. Let us take a look at it using an example.

Step 1 − Enter the data against which the graph has to be generated.

Step 2 − Create 3 buttons - one to generate a bar graph, another to generate a pie chart, and another to generate a column chart.

Step 3 − Develop a Macro to generate each one of these type of charts.

' Procedure to Generate Pie Chart
Private Sub fn_generate_pie_graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlPie
   Next cht
End Sub

' Procedure to Generate Bar Graph
Private Sub fn_Generate_Bar_Graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlBar
   Next cht
End Sub

' Procedure to Generate Column Graph
Private Sub fn_generate_column_graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlColumn
   Next cht
End Sub

Step 4 − Upon clicking the corresponding button, the chart is created. In the following output, click on generate Pie Chart button.

VBA - User Forms

A User Form is a custom-built dialog box that makes a user data entry more controllable and easier to use for the user. In this chapter, you will learn to design a simple form and add data into excel.

Step 1 − Navigate to VBA Window by pressing Alt+F11 and Navigate to "Insert" Menu and select "User Form". Upon selecting, the user form is displayed as shown in the following screenshot.

Step 2 − Design the forms using the given controls.

Step 3 − After adding each control, the controls have to be named. Caption corresponds to what appears on the form and name corresponds to the logical name that will be appearing when you write VBA code for that element.

Step 4 − Following are the names against each one of the added controls.

Step 5 − Add the code for the form load event by performing a right-click on the form and selecting 'View Code'.

Step 6 − Select ‘Userform’ from the objects drop-down and select 'Initialize' method as shown in the following screenshot.

Step 7 − Upon Loading the form, ensure that the text boxes are cleared, drop-down boxes are filled and Radio buttons are reset.

Private Sub UserForm_Initialize()
   'Empty Emp ID Text box and Set the Cursor 
   txtempid.Value = ""
   txtempid.SetFocus
   
   'Empty all other text box fields
   txtfirstname.Value = ""
   txtlastname.Value = ""
   txtemailid.Value = ""
   
   'Clear All Date of Birth Related Fields
   cmbdate.Clear
   cmbmonth.Clear
   cmbyear.Clear
   
   'Fill Date Drop Down box - Takes 1 to 31
   With cmbdate
      .AddItem "1"
      .AddItem "2"
      .AddItem "3"
      .AddItem "4"
      .AddItem "5"
      .AddItem "6"
      .AddItem "7"
      .AddItem "8"
      .AddItem "9"
      .AddItem "10"
      .AddItem "11"
      .AddItem "12"
      .AddItem "13"
      .AddItem "14"
      .AddItem "15"
      .AddItem "16"
      .AddItem "17"
      .AddItem "18"
      .AddItem "19"
      .AddItem "20"
      .AddItem "21"
      .AddItem "22"
      .AddItem "23"
      .AddItem "24"
      .AddItem "25"
      .AddItem "26"
      .AddItem "27"
      .AddItem "28"
      .AddItem "29"
      .AddItem "30"
      .AddItem "31"
   End With
   
   'Fill Month Drop Down box - Takes Jan to Dec
   With cmbmonth
      .AddItem "JAN"
      .AddItem "FEB"
      .AddItem "MAR"
      .AddItem "APR"
      .AddItem "MAY"
      .AddItem "JUN"
      .AddItem "JUL"
      .AddItem "AUG"
      .AddItem "SEP"
      .AddItem "OCT"
      .AddItem "NOV"
      .AddItem "DEC"
   End With
   
   'Fill Year Drop Down box - Takes 1980 to 2014
   With cmbyear
      .AddItem "1980"
      .AddItem "1981"
      .AddItem "1982"
      .AddItem "1983"
      .AddItem "1984"
      .AddItem "1985"
      .AddItem "1986"
      .AddItem "1987"
      .AddItem "1988"
      .AddItem "1989"
      .AddItem "1990"
      .AddItem "1991"
      .AddItem "1992"
      .AddItem "1993"
      .AddItem "1994"
      .AddItem "1995"
      .AddItem "1996"
      .AddItem "1997"
      .AddItem "1998"
      .AddItem "1999"
      .AddItem "2000"
      .AddItem "2001"
      .AddItem "2002"
      .AddItem "2003"
      .AddItem "2004"
      .AddItem "2005"
      .AddItem "2006"
      .AddItem "2007"
      .AddItem "2008"
      .AddItem "2009"
      .AddItem "2010"
      .AddItem "2011"
      .AddItem "2012"
      .AddItem "2013"
      .AddItem "2014"
   End With
   
   'Reset Radio Button. Set it to False when form loads.
   radioyes.Value = False
   radiono.Value = False

End Sub

Step 8 − Now add the code to the Submit button. Upon clicking the submit button, the user should be able to add the values into the worksheet.

Private Sub btnsubmit_Click()
   Dim emptyRow As Long
  
   'Make Sheet1 active
   Sheet1.Activate
  
   'Determine emptyRow
   emptyRow = WorksheetFunction.CountA(Range("A:A")) + 1
  
   'Transfer information
   Cells(emptyRow, 1).Value = txtempid.Value
   Cells(emptyRow, 2).Value = txtfirstname.Value
   Cells(emptyRow, 3).Value = txtlastname.Value
   Cells(emptyRow, 4).Value = cmbdate.Value & "/" & cmbmonth.Value & "/" & cmbyear.Value
   Cells(emptyRow, 5).Value = txtemailid.Value
  
   If radioyes.Value = True Then
      Cells(emptyRow, 6).Value = "Yes"
   Else
      Cells(emptyRow, 6).Value = "No"
   End If
End Sub

Step 9 − Add a method to close the form when the user clicks the Cancel button.

Private Sub btncancel_Click()
   Unload Me
End Sub

Step 10 − Execute the form by clicking the "Run" button. Enter the values into the form and click the 'Submit' button. Automatically the values will flow into the worksheet as shown in the following screenshot.