VB Script
(Fundamentals and Features)
1) Introduction
2) Comments
3) VB Script Variables
4) VB Script Data Types
5) VB Script Operators
6) Input/Output Operations
7) Constants
8) Conditional Statements
9) Loop through Code
10) Other Statements
11) Procedures
13) Errors
14) Built-In Functions
15) Regular Expressions
16) Methods
17) Objects
18) Properties
19) Classes
20) Keywords
21) VBScript syntax rules and guidelines
1.0 Introduction
· VBScript is a scripting language.
· A scripting language is a lightweight programming language.
· VBScript is a light version of Microsoft's programming language Visual Basic.
When a VBScript is inserted into a HTML document, the Internet browser will read the HTML and interpret the VBScript. The VBScript can be executed immediately, or at a later event.
Microsoft Visual Basic Scripting Edition brings active scripting to a wide variety of environments, including Web client scripting in Microsoft Internet Explorer and Web server scripting in Microsoft Internet Information Service.
1.1 Windows Script Host (WSH)
It is a Windows administration tool. WSH creates an environment for hosting scripts. That is, when a script arrives at your computer, WSH plays the part of the host — it makes objects and services available for the script and provides a set of guidelines within which the script is executed. Among other things, Windows Script Host manages security and invokes the appropriate script engine
Windows Script Host is built into Microsoft Windows 98, 2000, and Millennium Editions and higher versions.
A Windows script is a text file. We can create a script with any text editor as long as we save our script with a WSH-compatible script extension (.js, vbs, or .wsf).
The most commonly available text editor is already installed on our computer — Notepad. We can also use your favorite HTML editor, VbsEdit, Microsoft Visual C++, or Visual InterDev.
1.2 Creating a script with Notepad
1. Start Notepad.
2. Write your script. For example purposes, type Msgbox "Hello VB Script"
3. Save this text file with a .vbs extension (instead of the default .txt extension). For example, Hello.vbs
4. Navigate to the file you just saved, and double-click it.
5. Windows Script Host invokes the VB Script engine and runs your script. In the example, a message box is displayed with the message "Hello VB Script"
1.3 Hosting Environments and Script Engines
Scripts are often embedded in Web pages, either in an HTML page (on the client side) or in an ASP page (on the server side). In the case of a script embedded in an HTML page, the engine component that interprets and runs the script code is loaded by the Web browser, such as Internet Explorer. In the case of a script embedded in an ASP page, the engine that interprets and runs the script code is built into Internet Information Services (IIS).
Windows Script Host executes scripts that exist outside an HTML or ASP page and that stand on their own as text files.
1.4 Available Script Engines
Generally, we write scripts in either Microsoft JScript or VBScript, the two script engines that ship with Microsoft Windows 98, 2000 and Millennium Editions. We can use other script engines, such as Perl, REXX, and Python, with Windows Script Host.
A stand-alone script written in JScript has the .js extension; a stand-alone script written in VBScript has the .vbs extension. These extensions are registered with Windows. When we run one of these types of files, Windows starts Windows Script Host, which invokes the associated script engine to interpret and run the file.
2.0 Comments
The comment argument is the text of any comment we want to include.
2.0 Purpose of comments:
o We can use comments for making the script understandable.
o We can use comments for making one or more statements disable from execution.
2.1 Syntax
Rem comment (After the Rem keyword, a space is required before comment.)
Or
Apostrophe (') symbol before the comment
2.2 Comment/Uncomment a block of statements
o Select block of statement and use short cut key Ctrl + M (for comment)
o Select comment block and use short cut key Ctrl + Shift + M (for uncomment)
2.3 Example
3.0 VB Script Variables
A variable is a convenient placeholder that refers to a computer memory location where we can store program information that may change during the time our script is running.
3.1 Declaring Variables
We declare variables explicitly in our script using the Dim statement, the Public statement, and the Private statement.
For example:
Dim city
Dim x
We declare multiple variables by separating each variable name with a comma. For example:
Dim x, Top, Bottom, Left, Right
We can also declare a variable implicitly by simply using its name in our script. That is not generally a good practice because we could misspell the variable name in one or more places, causing unexpected results when our script is run. For that reason, the Option Explicit statement is available to require explicit declaration of all variables.
The Option Explicit statement should be the first statement in our script.
3.2 Option Explicit
Forces explicit declaration of all variables in a script.
Option Explicit ' Force explicit variable declaration.
Dim MyVar ' Declare variable.
MyInt = 10 ' Undeclared variable generates error.
MyVar = 10 ' Declared variable does not generate error.
3.3 Naming Restrictions for Variables
Variable names follow the standard rules for naming anything in VBScript. A variable name:
· Must begin with an alphabetic character.
· Cannot contain an embedded period.
· Must not exceed 255 characters.
· Must be unique in the scope in which it is declared.
3.4 Scope of Variables
o A variable's scope is determined by where you declare it.
o When we declare a variable within a procedure, only code within that procedure can access or change the value of that variable
o If we declare a variable outside a procedure, we make it recognizable to all the procedures in our script. This is a script-level variable, and it has script-level scope.
3.5 Life Time of Variables
o The lifetime of a variable depends on how long it exists.
o The lifetime of a script-level variable extends from the time it is declared until the time the script is finished running.
o At procedure level, a variable exists only as long as you are in the procedure.
3.6 Assigning Values to Variables
Values are assigned to variables creating an expression as follows:
The variable is on the left side of the expression and the value you want to assign to the variable is on the right.
For example:
B = 200
City = “Hyderabad”
3.7 Scalar Variables and Array Variables
A variable containing a single value is a scalar variable.
A variable containing a series of values, is called an array variable.
Array variables and scalar variables are declared in the same way, except that the declaration of an array variable uses parentheses () following the variable name.
Example:
Dim A(3)
Although the number shown in the parentheses is 3, all arrays in VBScript are zero-based, so this array actually contains 4 elements.
We assign data to each of the elements of the array using an index into the array. Beginning at zero and ending at 10, data can be assigned to the elements of an array as follows:
A(0) = 256
A(1) = 324
A(2) = 100
A(3) = 55
Similarly, the data can be retrieved from any element using an index into the particular array element you want.
For example:
SomeVariable = A(4)
Arrays aren't limited to a single dimension. You can have as many as 60 dimensions, although most people can't comprehend more than three or four dimensions.
Arrays aren't limited to a single dimension. We can have as many as 60 dimensions, although most people can't comprehend more than three or four dimensions.
In the following example, the MyTable variable is a two-dimensional array consisting of 6 rows and 11 columns:
Dim MyTable(5, 10)
In a two-dimensional array, the first number is always the number of rows; the second number is the number of columns.
3.8 Dynamic Arrays
We can also declare an array whose size changes during the time our script is running. This is called a dynamic array.
The array is initially declared within a procedure using either the Dim statement or using the ReDim statement.
However, for a dynamic array, no size or number of dimensions is placed inside the parentheses.
For example:
Dim MyArray()
ReDim AnotherArray()
To use a dynamic array, you must subsequently use ReDim to determine the number of dimensions and the size of each dimension.
In the following example, ReDim sets the initial size of the dynamic array to 25. A subsequent ReDim statement resizes the array to 30, but uses the Preserve keyword to preserve the contents of the array as the resizing takes place.
ReDim MyArray(25)
ReDim Preserve MyArray(30)
There is no limit to the number of times we can resize a dynamic array, although if we make an array smaller, we lose the data in the eliminated elements.
4.0 VB Script Data Types
VBScript has only one data type called a Variant. A Variant is a special kind of data type that can contain different kinds of information, depending on how it is used. Because Variant is the only data type in VBScript, it is also the data type returned by all functions in VBScript.
4.1 Variant Subtypes
Beyond the simple numeric or string classifications, a Variant can make further distinctions about the specific nature of numeric information. For example, we can have numeric information that represents a date or a time. When used with other date or time data, the result is always expressed as a date or a time. We can also have a rich variety of numeric information ranging in size from Boolean values to huge floating-point numbers. These different categories of information that can be contained in a Variant are called subtypes. Most of the time, we can just put the kind of data we want in a Variant, and the Variant behaves in a way that is most appropriate for the data it contains.
The following table shows subtypes of data that a Variant can contain.
Subtype Description
Empty Variant is uninitialized. Value is 0 for numeric variables or a zero-length string ("") for string variables.
Null Variant intentionally contains no valid data.
Boolean Contains either True or False.
Byte Contains integer in the range 0 to 255.
Integer Contains integer in the range -32,768 to 32,767.
Currency -922,337,203,685,477.5808 to 922,337,203,685,477.5807.
Long Contains integer in the range -2,147,483,648 to 2,147,483,647.
Single Contains a single-precision, floating-point number in the range -3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.402823E38 for positive values.
Double Contains a double-precision, floating-point number in the range -1.79769313486232E308 to -4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values.
Date (Time) Contains a number that represents a date between January 1, 100 to December 31, 9999.
String Contains a variable-length string that can be up to approximately 2 billion characters in length.
Object Contains an object.
Error Contains an error number.
We can use conversion functions to convert data from one subtype to another. In addition, the VarType function returns information about how your data is stored within a Variant.
5.0 VB Script Operators
Operators are used for performing mathematical, comparison and logical operations.
VBScript has a full range of operators, including arithmetic operators, comparison operators, concatenation operators, and logical operators.
4.1 Operator Precedence
When several operations occur in an expression, each part is evaluated and resolved in a predetermined order called operator precedence.
We can use parentheses to override the order of precedence and force some parts of an expression to be evaluated before others.
Operations within parentheses are always performed before those outside. Within parentheses, however, standard operator precedence is maintained.
When expressions contain operators from more than one category, arithmetic operators are evaluated first, comparison operators are evaluated next, and logical operators are evaluated last.
Comparison operators all have equal precedence; that is, they are evaluated in the left-to-right order in which they appear.
Arithmetic and logical operators are evaluated in the following order of precedence.
4.2 Arithmetic Operators:
Operator Description
1) Exponentiation Operator (^) Raises a number to the power of an exponent.
2) Multiplication Operator (*) Multiplies two numbers.
3) Division Operator (/) Divides two numbers and returns a floating-point result.
4) Integer Division Operator (\) Divides two numbers and returns an integer result.
5) Mod Operator Divides two numbers and returns only the remainder.
6) Addition Operator (+) Sums two numbers.
7) Subtraction Operator (-) Finds the difference between two numbers or indicates the negative value of a numeric expression.
8) Concatenation Operator (&) Forces string concatenation of two expressions.
4.3 Comparison Operators
Used to compare expressions.
Operator Description Operator Description
1) = Equal to 5) <= Less than or equal to
2) <> Not equal to 6) >= Greater than or equal to
3) < Less than 7) Is Object equivalence
4) > Grater than
4.4 Concatenation Operators
Operator Description
1) Addition Operator (+) Sums two numbers.
If Then
1) Both expressions are numeric Add.
2) Both expressions are strings Concatenate.
3) One expression is numeric and the other is a string Add.
2) Concatenation Operator (&) Forces string concatenation of two expressions.
4.5 Logical Operators
Operator Description Syntax
1) Not Performs logical negation on an expression. result= Not expression
2) And Performs a logical conjunction on two expressions. result= expression1 And expression2
3) Or Performs a logical disjunction on two expressions. result= expression1 Or expression2
4) Xor Performs a logical exclusion on two expressions. result= expression1 Xor expression2
5) Eqv Performs a logical equivalence on two expressions. result= expression1 Eqv expression2
6) Imp Performs a logical implication on two expressions. result= expression1 Imp expression2
6) Input/Output Operations
6.1 InputBox Function
Displays a prompt in a dialog box, waits for the user to input text or click a button, and returns the contents of the text box.
Example:
Dim Input
Input = InputBox("Enter your name")
MsgBox ("You entered: " & Input)
6.2 MsgBox Function
Displays a message in a dialog box, waits for the user to click a button, and returns a value indicating which button the user clicked.
Example:
Dim MyVar
MyVar = MsgBox ("Hello World!", 65, "MsgBox Example")
' MyVar contains either 1 or 2, depending on which button is clicked.
7) VB Script Constants
A constant is a meaningful name that takes the place of a number or string and never changes.
7.1 Creating Constants
We create user-defined constants in VBScript using the Const statement. Using the Const statement, we can create string or numeric constants with meaningful names and assign them literal values.
Const statement
Declares constants for use in place of literal values.
Example:
Const MyString = "This is my string."
Const MyAge = 49
Const CutoffDate = #6-1-97#
Note that String literal is enclosed in quotation marks (" ").
Represent Date literals and time literals by enclosing them in number signs (#).
We declare multiple constants by separating each constant name and value with a comma. For example:
Const price= 100, city= “Hyderabad”, x= 27
8) Conditional Statements
We can control the flow of our script with conditional statements and looping statements.
Using conditional statements, we can write VBScript code that makes decisions and repeats actions. The following conditional statements are available in VBScript:
1) If…Then…Else Statement
2) Select Case Statement
8.1 Making Decisions Using If...Then...Else
The If...Then...Else statement is used to evaluate whether a condition is True or False and, depending on the result, to specify one or more statements to run. Usually the condition is an expression that uses a comparison operator to compare one value or variable with another.
If...Then...Else statements can be nested to as many levels as you need.
8.1.1 Running a Statements if a Condition is True (single statement)
To run only one statement when a condition is True, use the single-line syntax for the If...Then...Else statement.
Dim myDate
myDate = #2/13/98#
If myDate < Now Then myDate = Now
8.1.2 Running Statements if a Condition is True (multiple statements)
To run more than one line of code, we must use the multiple-line (or block) syntax. This syntax includes the End If statement.
Dim x
x= 20
If x>10 Then
msgbox "Hello"
msgbox "x value is: "&x
msgbox "Bye"
End If
8.1.3 Running Certain Statements if a Condition is True and Running Others if a Condition is False
We can use an If...Then...Else statement to define two blocks of executable statements: one block to run if the condition is True, the other block to run if the condition is False.
Example:
Dim x
x= Inputbox (" Enter a value")
If x>100 Then
Msgbox "Hello"
Msgbox "X is a Big Number"
Msgbox "X value is: "&X
Else
Msgbox "Output"
Msgbox "X is a Small Number"
Msgbox "X value is: "&X
End If
8.1.4 Deciding Between Several Alternatives
A variation on the If...Then...Else statement allows us to choose from several alternatives. Adding ElseIf clauses expands the functionality of the If...Then...Else statement so we can control program flow based on different possibilities.
Example:
Dim x
x= Inputbox (" Enter a value")
If x>0 and x<=100 Then
Msgbox "Hello"
Msgbox "X is a Small Number"
Msgbox "X value is "&x
Else IF x>100 and x<=500 Then
Msgbox "Hello Rose"
Msgbox "X is a Medium Number"
Else IF x>500 and x<=1000 Then
Msgbox "Hello Kim"
Msgbox "X is a Large Number"
Else
Msgbox "Hello Jack"
Msgbox "X is a Grand Number"
End If
End If
End If
8.1.5 Executing a certain block of statements when two / more conditions are True (Nested If...)
Example:
Dim State, Region
State=Inputbox ("Enter a State")
Region=Inputbox ("Enter a Region")
If state= "AP" Then
If Region= "Telangana" Then
msgbox "Hello A"
msgbox "Dist count is 10"
Else if Region= "Rayalasema" Then
msgbox "Hello B"
msgbox "Dist count is 4"
Else If Region= "Costal" Then
msgbox "Hello C"
msgbox "Dist count is 9"
End If
End If
End If
End If
8.2 Making Decisions with Select Case
The Select Case structure provides an alternative to If...Then...ElseIf for selectively executing one block of statements from among multiple blocks of statements. A Select Case statement provides capability similar to the If...Then...Else statement, but it makes code more efficient and readable.
Example:
Option explicit
Dim x,y, Operation, Result
x= Inputbox (" Enter x value")
y= Inputbox ("Enter y value")
Operation= Inputbox ("Enter an Operation")
Select Case Operation
Case "add"
Result= cdbl (x)+cdbl (y)
Msgbox "Hello Tim"
Msgbox "Addition of x,y values is "&Result
Case "sub"
Result= x-y
Msgbox "Hello Tim"
Msgbox "Substraction of x,y values is "&Result
Case "mul"
Result= x*y
Msgbox "Hello Tim"
Msgbox "Multiplication of x,y values is "&Result
Case "div"
Result= x/y
Msgbox "Hello Tim"
Msgbox "Division of x,y values is "&Result
Case "mod"
Result= x mod y
Msgbox "Hello Tim"
Msgbox "Mod of x,y values is "&Result
Case "expo"
Result= x^y
Msgbox "Hello Tim"
Msgbox"Exponentation of x,y values is "&Result
Case Else
Msgbox "Hello Tim"
msgbox "Wrong Operation"
End Select
8.3 Other Examples
8.3.1 Write a program for finding out whether the given year is a leap year or not?
Dim xyear
xyear=inputbox ("Enter Year")
If xyear mod 4=0 Then
msgbox "This is a Leap year"
Else
msgbox "This is NOT"
End If
8.3.2 Write a program for finding out whether the given number is, Even number or Odd number?
Dim num
num=inputbox ("Enter a number")
If num mod 2=0 Then
msgbox "This is a Even Number"
Else
msgbox "This is a Odd Number"
End If
8.3.3 Read two numbers and display the sum?
Dim num1,num2, sum
num1=inputbox ("Enter num1")
num2=inputbox ("Enter num2")
sum= Cdbl (num1) + Cdbl (num2) 'if we want add two strings conversion require
msgbox ("Sum is " &sum)
8.3.4 Read P,T,R values and Calculate the Simple Interest?
Dim p,t, r, si
p=inputbox ("Enter Principle")
t=inputbox ("Enter Time")
r=inputbox ("Enter Rate of Interest")
si= (p*t*r)/100 ' p= principle amount, t=time in years, r= rate of interest
msgbox ("Simple Interest is " &si)
8.3.5 Read Four digit number, calculate & display the sum of the number or display Error message if the number is not a four digit number?
Dim num, sum
num=inputbox ("Enter a Four digit number")
If Len(num) = 4 Then
sum=0
sum=sum+num mod 10
num=num/10
num= left (num, 3)
sum=sum+num mod 10
num=num/10
num= left (num, 2)
sum=sum+num mod 10
num=num/10
num= left (num, 1)
sum=sum+num mod 10
msgbox ("Sum is " &sum)
else
msgbox "Number, you entered is not a 4 digit number"
End If
8.3.6 Read any Four digit number and display the number in reverse order?
Dim num,rev
num= inputbox("Enter a number")
If len(num)=4 Then
rev=rev*10 + num mod 10
num=num/10
num= left(num,3)
rev=rev*10 + num mod 10
num=num/10
num= left(num,2)
rev=rev*10 + num mod 10
num=num/10
num= left(num,1)
rev=rev*10 + num mod 10
msgbox "Reverse Order of the number is "&rev
Else
msgbox "Number, you entered is not a 4 digit number"
End If
8.3.7 Read 4 subjects marks; calculate the Total marks and grade?
(a) If average marks Greater than or equal to 75, grade is Distinction
b) If average marks Greater than or equal to 60 and less than 75 , then grade is First
c) If average marks Greater than or equal to 50 and less than 60 , then grade is Second
d) If average marks Greater than or equal to 40 and less than 50 , then grade is Third
e) Minimum marks 35 for any subject, otherwise 'no grade fail')
Dim e,m,p,c, tot
e=inputbox ("Enter english Marks")
m=inputbox ("Enter maths Marks")
p=inputbox ("Enter physics Marks")
c=inputbox ("Enter chemistry Marks")
tot= cdbl(e) + cdbl(m) + cdbl(p) + cdbl(c)
msgbox tot
If cdbl(e) >=35 and cdbl(m) >=35 and cdbl(p) >=35 and cdbl(c) >=35 and tot >=300 Then
msgbox "Grade is Distinction"
else If cdbl(e) >=35 and cdbl(m) >=35 and cdbl(p) >=35 and cdbl(c) >=35 and tot >=240 and tot<300 Then
msgbox "Grade is First"
else If cdbl(e) >=35 and cdbl(m) >=35 and cdbl(p) >=35 and cdbl(c) >=35 and tot >=200 and tot<240 Then
msgbox "Grade is Second"
else If cdbl(e) >=35 and cdbl(m) >=35 and cdbl(p) >=35 and cdbl(c) >=35 and tot >=160 and tot<200 Then
msgbox "Grade is Third"
else
msgbox "No Grade, Fail"
End If
End If
End If
End If
8.3.8 Display Odd numbers up to n?
Dim num,n
n=Inputbox ("Enter a Vaule")
For num= 1 to n step 2
msgbox num
Next
8.3.9 Display Even numbers up to n?
Dim num,n
n=Inputbox ("Enter a Vaule")
For num= 2 to n step 2
msgbox num
Next
8.3.10 display natural numers up to n and write in a text file?
Dim num, n, fso, myfile
n= inputbox ("Enter any Value")
num=1
For num= 1 to n step 1
Set fso= createobject ("scripting.filesystemobject")
set myfile=fso.opentextfile ("E:\gcr.txt", 8, true)
myfile.writeline num
myfile.close
Next
8.11 Display Natural numbers in reverse order up to n?
Dim num,n
n=Inputbox ("Enter a Vaule")
For num=n to 1 step -1
msgbox num
Next
8.12 Display Natural numbers sum up to n? (using For...Next Loop)
Dim num, n, sum
n= inputbox ("Enter a Value")
sum=0
For num= 1 to n step 1
sum= sum+num
Next
msgbox sum
8.13 Display Natural numbers sum up to n? (using While...Wend Loop)
Dim num, n, sum
n= inputbox ("Enter a Value")
While num <=cdbl (n)
sum= sum+num
num=num+1
Wend
msgbox sum
8.14 Display Natural numbers sum up to n? (using Do...Until...Loop)
Dim num, n, sum
n= inputbox ("Enter a Value")
sum=0
num=1
Do
sum= sum+num
num=num+1
Loop Until num =cdbl (n+1)
msgbox sum
8.15 Write a Function for Natural Numbers sum up to n?
Function NNumCou (n)
Dim num, sum
sum=0
For num= 1 to n step 1
sum= sum+num
Next
msgbox sum
End Function
8.16 Verify weather the entered 10 digit value is a numeric value or not?
Dim a,x,y,z,num
num=Inputbox ("Enter a Phone Number")
d1= left (num,1)
d10=Right (num,1)
d2=mid (num, 2, len (1))
d3=mid (num, 3, len (1))
d4=mid (num, 4, len (1))
d5=mid (num, 5, len (1))
d6=mid (num, 6, len (1))
d7=mid (num, 7, len (1))
d8=mid (num, 8, len (1))
d9=mid (num, 9, len (1))
If isnumeric (d1) = "True" and isnumeric (d2) = "True" and isnumeric (d3) = "True" and isnumeric (d4) = "True"and isnumeric (d5) = "True"and isnumeric (d6) = "True"and isnumeric (d7) = "True"and isnumeric (d8) = "True"and isnumeric (d9) = "True"and isnumeric (d10) = "True" Then
msgbox "It is a Numeric Value"
else
Msgbox "It is NOT Numeric"
End If
8.17 Verify weather the entered value is a 10 digit value or not and Numeric value or not? (using multiple if conditions)
Dim a,x,y,z,num
num=Inputbox ("Enter a Phone Number")
d1= left (num,1)
d10=Right (num,1)
d2=mid (num, 2, len (1))
d3=mid (num, 3, len (1))
d4=mid (num, 4, len (1))
d5=mid (num, 5, len (1))
d6=mid (num, 6, len (1))
d7=mid (num, 7, len (1))
d8=mid (num, 8, len (1))
d9=mid (num, 9, len (1))
If len (num) =10 Then
If isnumeric (d1) = "True" and isnumeric (d2) = "True" and isnumeric (d3) = "True" and isnumeric (d4) = "True"and isnumeric (d5) = "True"and isnumeric (d6) = "True"and isnumeric (d7) = "True"and isnumeric (d8) = "True"and isnumeric (d9) = "True"and isnumeric (d10) = "True" Then
msgbox "It is a Numeric Value"
End If
End If
If len (num) <> 10 Then
Msgbox "It is NOT valid Number "
End If
9) Looping Through Code
o Looping allows us to run a group of statements repeatedly.
o Some loops repeat statements until a condition is False;
o Others repeat statements until a condition is True.
o There are also loops that repeat statements a specific number of times.
The following looping statements are available in VBScript:
· Do...Loop: Loops while or until a condition is True.
· While...Wend: Loops while a condition is True.
· For...Next: Uses a counter to run statements a specified number of times.
· For Each...Next: Repeats a group of statements for each item in a collection or each element of an array.
9.1 Using Do Loops
We can use Do...Loop statements to run a block of statements an indefinite number of times. The statements are repeated either while a condition is True or until a condition becomes True.
9.1.1 Repeating Statements While a Condition is True
Repeats a block of statements while a condition is True or until a condition becomes True
a) Do While condition
Statements
-----------
-----------
Loop
Or, we can use this below syntax:
Example:
Dim x
Do While x<5 x=x+1
Msgbox "Hello"
Msgbox "Hello QTP"
Loop
b) Do
Statements
-----------
-----------
Loop While condition
Example:
Dim x
x=1
Do
Msgbox "Hello"
Msgbox "Hello QTP"
x=x+1
Loop While x<5
9.1.2 Repeating a Statement Until a Condition Becomes True
c) Do Until condition
Statements
-----------
-----------
Loop
Or, we can use this below syntax:
Example:
Dim x
Do Until x=5 x=x+1
Msgbox "ABC"
Msgbox "Hello QTP"
Loop
Or, we can use this below syntax:
d) Do
Statements
-----------
-----------
Loop Until condition
Or, we can use this below syntax:
Example:
Dim x
x=1
Do
Msgbox “Hello”
Msgbox "Hello QTP"
x=x+1
Loop Until x=5
9.2 While...Wend Statement
Executes a series of statements as long as a given condition is True.
Syntax:
While condition
Statements
-----------
-----------
Wend
Example:
Dim x
x=0
While x<5 x=x+1
msgbox "Hello"
msgbox "Hello QTP"
Wend
9.3 For...Next Statement
Repeats a group of statements a specified number of times.
Syntax:
For counter = start to end [Step step]
statements
Next
Example:
Dim x
For x= 1 to 5 step 1
Msgbox "Hello"
Next
9.4 For Each...Next Statement
Repeats a group of statements for each element in an array or collection.
Syntax:
For Each item In array
Statements
Next
Example:
Dim a,b,x (3)
a=20
b=30
x(0)= "Addition is "& a+b
x(1)="Substraction is " & a-b
x(2)= "Multiplication is " & a*b
x(3)= "Division is " & a/b
For Each element In x
msgbox element
Next
Example:
MyArray = Array("one","two","three","four","five")
For Each element In MyArray
msgbox element
Next
11) VB Script Procedures
In VBScript, there are two kinds of procedures; the Sub procedure and the Function procedure.
11.1 Sub Procedures
A Sub procedure is a series of VBScript statements (enclosed by Sub and End Sub statements) that perform actions but don't return a value.
A Sub procedure can take arguments (constants, variables, or expressions that are passed by a calling procedure).
If a Sub procedure has no arguments, its Sub statement must include an empty set of parentheses ().
Syntax:
Sub Procedure name ()
Statements
-----------
-----------
End Sub
Or
Sub Procedure name (argument1, argument2)
Statements
-----------
-----------
End Sub
Example: 1
Sub ConvertTemp()
temp = InputBox("Please enter the temperature in degrees F.", 1)
MsgBox "The temperature is " & Celsius(temp) & " degrees C."
End Sub
Example: 2
11.2 Function Procedures
A Function procedure is a series of VBScript statements enclosed by the Function and End Function statements.
A Function procedure is similar to a Sub procedure, but can also return a value.
A Function procedure can take arguments (constants, variables, or expressions that are passed to it by a calling procedure).
If a Function procedure has no arguments, its Function statement must include an empty set of parentheses.
A Function returns a value by assigning a value to its name in one or more statements of the procedure. The return type of a Function is always a Variant.
Syntax:
Function Procedure name ()
Statements
-----------
-----------
End Function
Or
Function Procedure name (argument1, argument2)
Statements
-----------
-----------
End Function
Example: 1
Function Celsius(fDegrees)
Celsius = (fDegrees - 32) * 5 / 9
End Function
Example: 2
Function cal(a,b,c)
cal = (a+b+c)
End Function
11.3 Getting Data into and out of Procedures
o Each piece of data is passed into our procedures using an argument.
o Arguments serve as placeholders for the data we want to pass into our procedure. We can name our arguments any valid variable name.
o When we create a procedure using either the Sub statement or the Function statement, parentheses must be included after the name of the procedure.
o Any arguments are placed inside these parentheses, separated by commas.
11.4 Using Sub and Function Procedures in Code
A Function in our code must always be used on the right side of a variable assignment or in an expression.
For example:
Temp = Celsius(fDegrees)
-Or-
MsgBox "The Celsius temperature is " & Celsius(fDegrees) & " degrees."
To call a Sub procedure from another procedure, type the name of the procedure along with values for any required arguments, each separated by a comma.
The Call statement is not required, but if you do use it, you must enclose any arguments in parentheses.
The following example shows two calls to the MyProc procedure. One uses the Call statement in the code; the other doesn't. Both do exactly the same thing.
Call MyProc(firstarg, secondarg)
MyProc firstarg, secondarg
Notice that the parentheses are omitted in the call when the Call statement isn't used.
9) VB Script Built in Functions
1) Abs Function
Returns the absolute value of a number.
Abs(number)
The number argument can be any valid numeric expression. If number contains Null, Null is returned; if it is an uninitialized variable, zero is returned.
The following example uses the Abs function to compute the absolute value of a number:
Dim MyNumber
MyNumber = Abs(50.3) ' Returns 50.3.
MyNumber = Abs(-50.3) ' Returns 50.3.
2) Array Function
Returns a Variant containing an array.
Array(arglist)
Example:
Dim A
A = Array(10,20,30)
B = A(2) ' B is now 30.
Note A variable that is not declared as an array can still contain an array. Although a Variant variable containing an array is conceptually different from an array variable containing Variant elements, the array elements are accessed in the same way.
3) CBool Function
Returns an expression that has been converted to a Variant of subtype Boolean.
CBool(expression)
The expression argument is any valid expression.
Remarks
If expression is zero, False is returned; otherwise, True is returned. If expression can't be interpreted as a numeric value, a run-time error occurs.
The following example uses the CBool function to convert an expression to a Boolean. If the expression evaluates to a nonzero value, CBool returns True; otherwise, it returns False.
Dim A, B, Check
A = 5: B = 5 ' Initialize variables.
Check = CBool(A = B) ' Check contains True.
A = 0 ' Define variable.
Check = CBool(A) ' Check contains False.
4) CByte Function
Returns an expression that has been converted to a Variant of subtype Byte.
CByte(expression)
The expression argument is any valid expression.
Example of use
Dim MyDouble, MyByte
MyDouble = 125.5678 ' MyDouble is a Double.
MyByte = CByte(MyDouble) ' MyByte contains 126.
5) CCur Function
Returns an expression that has been converted to a Variant of subtype Currency.
CCur(expression)
The expression argument is any valid expression.
The following example uses the CCur function to convert an expression to a Currency:
Dim MyDouble, MyCurr
MyDouble = 543.214588 ' MyDouble is a Double.
MyCurr = CCur(MyDouble * 2) ' Convert result of MyDouble * 2 (1086.429176) to a Currency (1086.4292).
6) CDate Function
Returns an expression that has been converted to a Variant of subtype Date.
CDate(date)
The date argument is any valid date expression.
Example:
MyDate = "October 19, 1962" ' Define date.
MyShortDate = CDate(MyDate) ' Convert to Date data type.
MyTime = "4:35:47 PM" ' Define time.
MyShortTime = CDate(MyTime) ' Convert to Date data type.
7) CDbl Function
Returns an expression that has been converted to a Variant of subtype Double.
CDbl(expression)
The expression argument is any valid expression.
This example uses the CDbl function to convert an expression to a Double.
Dim MyCurr, MyDouble
MyCurr = CCur(234.456784) ' MyCurr is a Currency (234.4567).
MyDouble = CDbl(MyCurr * 8.2 * 0.01) ' Convert result to a Double (19.2254576).
8) Cos Function
Returns the cosine of an angle.
Cos(number)
The number argument can be any valid numeric expression that expresses an angle in radians.
The following example uses the Cos function to return the cosine of an angle:
Dim MyAngle, MySecant
MyAngle = 1.3 ' Define angle in radians.
MySecant = 1 / Cos(MyAngle) ' Calculate secant.
9) Date Function
Returns the current system date.
Date
The following example uses the Date function to return the current system date:
Dim MyDate
MyDate = Date ' MyDate contains the current system date.
21) VBScript syntax rules and guidelines
21.1 Case-sensitivity:
By default, VBScript is not case sensitive and does not differentiate between upper-case and lower-case spelling of words, for example, in variables, object and method names, or constants.
For example, the two statements below are identical in VBScript:
Browser("Mercury").Page("Find a Flight:").WebList("toDay").Select "31"
browser("mercury").page("find a flight:").weblist("today").select "31"
21.2 Text strings:
When we enter a value as a text string, we must add quotation marks before and after the string. For example, in the above segment of script, the names of the Web site, Web page, and edit box are all text strings surrounded by quotation marks.
Note that the value 31 is also surrounded by quotation marks, because it is a text string that represents a number and not a numeric value.
In the following example, only the property name (first argument) is a text string and is in quotation marks. The second argument (the value of the property) is a variable and therefore does not have quotation marks. The third argument (specifying the timeout) is a numeric value, which also does not need quotation marks.
Browser("Mercury").Page("Find a Flight:").WaitProperty("items count", Total_Items, 2000)
21.3 Variables:
We can specify variables to store strings, integers, arrays and objects. Using variables helps to make our script more readable and flexible
21.4 Parentheses:
To achieve the desired result and to avoid errors, it is important that we use parentheses () correctly in our statements.
21.5 Indentation:
We can indent or outdent our script to reflect the logical structure and nesting of the statements.
21.6 Comments:
We can add comments to our statements using an apostrophe ('), either at the beginning of a separate line, or at the end of a statement. It is recommended that we add comments wherever possible, to make our scripts easier to understand and maintain.
21.7 Spaces:
We can add extra blank spaces to our script to improve clarity. These spaces are ignored by VBScript.
13) Errors
We have two types Errors in VB Script; they are VBScript Run-time Errors and VBScript Syntax Errors
13.1 VBScript Run-time Errors
VBScript run-time errors are errors that result when our VBScript script attempts to perform an action that the system cannot execute. VBScript run-time errors occur while our script is being executed; when variable expressions are being evaluated, and memory is being dynamic allocated.
Error Number Description
429 ActiveX component can't create object
507 An exception occurred
449 Argument not optional
17 Can't perform requested operation
430 Class doesn't support Automation
506 Class not defined
11 Division by zero
48 Error in loading DLL
5020 Expected ')' in regular expression
5019 Expected ']' in regular expression
432 File name or class name not found during Automation operation
92 For loop not initialized
5008 Illegal assignment
51 Internal error
505 Invalid or unqualified reference
481 Invalid picture
5 Invalid procedure call or argument
5021 Invalid range in character set
94 Invalid use of Null
448 Named argument not found
432 File name or class name not found during Automation operation
447 Object doesn't support current locale setting
445 Object doesn't support this action
438 Object doesn't support this property or method
451 Object not a collection
504 Object not safe for creating
503 Object not safe for initializing
502 Object not safe for scripting
424 Object required
91 Object variable not set
7 Out of Memory
28 Out of stack space
14 Out of string space
6 Overflow
35 Sub or function not defined
9 Subscript out of range
5017 Syntax error in regular expression
462 The remote server machine does not exist or is unavailable
10 This array is fixed or temporarily locked
13 Type mismatch
5018 Unexpected quantifier
500 Variable is undefined
458 Variable uses an Automation type not supported in VBScript
450 Wrong number of arguments or invalid property assignment
13.2 VBScript Syntax Errors
VBScript syntax errors are errors that result when the structure of one of our VBScript statements violates one or more of the grammatical rules of the VBScript scripting language. VBScript syntax errors occur during the program compilation stage, before the program has begun to be executed.
Error Number Description
1052 Cannot have multiple default property/method in a Class
1044 Cannot use parentheses when calling a Sub
1053 Class initialize or terminate do not have arguments
1058 'Default' specification can only be on Property Get
1057 'Default' specification must also specify 'Public'
1005 Expected '('
1006 Expected ')'
1011 Expected '='
1021 Expected 'Case'
1047 Expected 'Class'
1025 Expected end of statement
1014 Expected 'End'
1023 Expected expression
1015 Expected 'Function'
1010 Expected identifier
1012 Expected 'If'
1046 Expected 'In'
1026 Expected integer constant
1049 Expected Let or Set or Get in property declaration
1045 Expected literal constant
1019 Expected 'Loop'
1020 Expected 'Next'
1050 Expected 'Property'
1022 Expected 'Select'
1024 Expected statement
1016 Expected 'Sub'
1017 Expected 'Then'
1013 Expected 'To'
1018 Expected 'Wend'
1027 Expected 'While' or 'Until'
1028 Expected 'While,' 'Until,' or end of statement
1029 Expected 'With'
1030 Identifier too long
1014 Invalid character
1039 Invalid 'exit' statement
1040 Invalid 'for' loop control variable
1013 Invalid number
1037 Invalid use of 'Me' keyword
1038 'loop' without 'do'
1048 Must be defined inside a Class
1042 Must be first statement on the line
1041 Name redefined
1051 Number of arguments must be consistent across properties specification
1001 Out of Memory
1054 Property Set or Let must have at least one argument
1002 Syntax error
1055 Unexpected 'Next'
1015 Unterminated string constant
