Introduction to Regular Expressions in VBScript

This post talks about regular expressions in VBScript, regular expressions in UFT, regular expressions in VBScript examples, regular expressions in UFT examples, using regular expressions in VBScript, using regular expressions in UFT, VBScript RegExp Object, UFT RegExp Object, regular Expression, How to use regular expression.

VBScript does not support regular expression constant (/a pattern/ ). VBScript provides a pattern properly of a RagExp object.

Regular Expressions in QTP/UFT/VBScript:

What is Regular Expression?

It is a way of representing data using symbols. They are often used within matching, searching or replacing algorithms. Regular expressions enable us to perform the following tasks.

• Pattern matching and replace.
• Searching and replace.
• Replace
• Identifying required number or string

Text strings get assigned to the pattern property of a RegEx object.

Regular Expressions in QTP/UFT:

Regular expressions can be used in QTP/UFT for identifying objects and text strings with varying values.

Where we use regular expression:

o Defining the property values of an object in Descriptive programming for  handling dynamic objects
o For parameterizing a step
o creating checkpoints with varying values

Using Regular Expressions in QTP or UFT:

We can define a regular expression for a constant value, a Data Table parameter value, an Environment parameter value, or a property value in Descriptive programming.

We can define a regular expression in a standard checkpoint to verify the property values of an object; we can set the expected value of an object’s property as a regular expression so that an object with a varying value can be verified.

We can define the text string as a regular expression when creating a text checkpoint to check that a varying text string is displayed on our application,
For XML checkpoints we can set attribute or element values as regular expressions.

RegExp object

VB Script is providing RegExp object for defining Regular expressions, It provides simple support for defining regular expressions. RegExp comes with predefined properties and methods.
Regular Expression Object Properties and Methods:
Properties:
a) Global Property
b) IgnoreCase Property
c) Pattern Property
Methods:
a) Execute() Method
b) Replace() Method
c) Test() Method

Global Property

The global property accepts two values.

• True– it signifies the search will happen to the entire string.
• False– searches for the first occurrence

Syntax

Object.Global= value

By default global property is set to false. The Boolean value determines whether all occurrences of a pattern should be replaced.

Example with /b switch and without /b switch

IgnoreCase Property

This is helpful when we want to search a text.(In case – insensitive manner). Ignore case property accept two values.

• True– it will not ignore the case while searching
• False– it will make the search case sensitive

syntax-

Object.IgnoreCase= value

The Boolean value determines whether a case-sensitive search needs to be performed.

Dim reg, strString
Set reg=New RegExp
reg.Pattern="/b of" //(/b matches the exact word)
reg.Global=True
reg.IgnoreCase=True
strString="To take OF is not easy of the ground."
msgbox reg.Replace(strString,"off")

O/P- To take off is not easy on the ground.

Pattern Property

The pattern property takes the flags and text pattern that needs to be searched. This property sets or returns the regular expression that needs to be searched.

syntax-

Object.Pattern=[(flag info)("Search String/search info")]

The argument can be a string or a regular expression itself. Flag info is optional here.

Regular Expressions Examples or How to use Regular Expression?

1. We need to create a new regular expression object

   set myVar=New RegExp

2. We need to provide the key that needs to be matched.

   myVar.pattern="[[mySearchText]]"

3. myLine-  “the line or string from where the matching will happen”
4. Ask VBscript engine to perform the pattern matching and perform your task.

   msgbox myVar.Replace( myLine,[[text after replacement]])

Example of Regular Expression

Dim myVar,myLine
Set myVar=New RegExp //regular expression object
myVar.Pattern="boy" //creates pattern
myLine="every boy is great" //initial line
msgbox myVar.Replace( myLine,"girl")

o/p- every girl is great

How to make it dynamic?

We can make it dynamic by introducing an input box.regular expressions in VBScript examples

Dim myVar, myLine, myWord
Set myVar=New RegExp
myLine= inputbox(" Enter your line")
myVar.pattern= inputbox(" enter a word to change")
myWord= inputbox(" enter a word that will be final")
msgbox  myVar.replace( myLine, myWord)

For more dynamic behavior we can create a function, it will help us achieve CD-CT-CI.
It will also help in unattended execution.

regular expressions in VBScript examples/VBScript RegExp Object

Function ChangeLine(sLine, sWordToReplace, sNewWord)
Dim myVar,myLine,myWord
Set myVar==New RegExp
myLine=sline
myVar.Pattern= sWordToReplace
myWord=sNewWord
ChangeLine=myVar.Replace( myLine, myWord)
End function

The above example will only change the first occurrence of the word in the line. But if the line has many words( that needs to be changed) it will not work fully. We need to change the script a little bit.

myVar.Pattern= "switch and the search word"
myVar.Global= True

Switch mainly used is /b (word boundary)
The Global property ensures match in all occurrence of the word.

1) Match File Names in a Directory against Regular Expression

regular expressions in VBScript examples/VBScript RegExp Object

Set objFS = CreateObject("Scripting.FileSystemObject")
Set objShell = CreateObject("WScript.Shell")
strCurrentDirectory = objShell.CurrentDirectory
Set objFolder = objFS.GetFolder(strCurrentDirectory)
Set colFiles = objFolder.Files
Set objRE = New RegExp
objRE.Global     = True
objRE.IgnoreCase = False
objRE.Pattern    = WScript.Arguments(0)
For Each objFile In colFiles
bMatch = objRE.Test(objFile.Name)
If bMatch Then
WScript.Echo objFile.Name
End If
Next

2) Match Content in a File against a Regular Expression

regular expressions in VBScript examples/VBScript RegExp Object

strFileName = "E:test.txt"
Set objFS = CreateObject("Scripting.FileSystemObject")
Set objTS = objFS.OpenTextFile(strFileName)
strFileContents = objTS.ReadAll
WScript.Echo "Searching Within: "
WScript.Echo strFileContents
objTS.Close
Set objRE = New RegExp
objRE.Global     = True
objRE.IgnoreCase = False
objRE.Pattern    = WScript.Arguments(0)
Set colMatches = objRE.Execute(strFileContents)
WScript.Echo vbNewLine & "Resulting Matches:"
For Each objMatch In colMatches
WScript.Echo "At position " & objMatch.FirstIndex & " matched " & objMatch.Value

3. Replace Function

regular expressions in VBScript examples/VBScript RegExp Object

Dim myPattern,myString 
Set myPattern=new RegExp
myPattern.pattern="[2,3,4,5,6,7]
myString="I have 2 glasses with 3 tablespoon" 
msgbox myPattern.Replace (myString,"many")

4. How to match digit characters with a regular expressions?

regular expressions in VBScript examples/VBScript RegExp Object

Dim myReg,myString
Set myReg=New RegExp
myReg.Pattern="[0123456789]" //this is for specific
myReg.Pattern="[0-9]" //this is for generic
myReg.Pattern="/d" //this is for generic
myString="There are 5 persons in the car"
msgbox myReg.Replace(myString,"Many")

O/P- There are many persons in the car.

5.How not to match a digit in a regular expression?

A caret (^) or a circumflex sign does the trick here.

“[^,0-9]”=> will not match any digit in the range 0-9
“[^\d]”=> does the same
“[\D]”=> does the same

How to create a pattern or range in a regular expression?

While the above example like”[ 0 1 2 3 4 5 6 7 8 9]”or “[0-9]” or “/d” provides a generic pattern.We can create our own pattern by providing range or repeat count.

• “\d” implies \d{1} that is single digit
• “\d{2}” implies double digit
• “\d{3}” implies three digit

How to specify minimum number or range using regular expression?

• “\d+”=>implies that one or more digits equivalent to\d{1,}
• “\d*”=>implies that zero or more digits equivalent to \d{0,}
• “\d?”=>implies that zero or one  equivalent to \d{0,1}

we need to be careful using the last two.In order to change all the digits in the given string we need to Set global property as true.

Remembered matches(regular expressions in vbscript)

This technique is useful when one or all of the text matches, with our pattern while finding or replacing text.

regular expressions in vbscript examples/VBScript RegExp Object

Dim myReg,myString,myCol,matchFound 
Set myReg=New RegExp
myReg.Global=True
myReg.Pattern="http://(\w+[\w-]*\w+\.)*\w+"
myString="http://www.google.com"
myString=myString&VBcrlf & "http://www.bing.com"
myString=myString&VBcrlf & "http://www.altavista.com"
Set myCol=myReg.Execute(myString)
For Each matchFound in myCol
   msgbox "Found valid URL" & matchFound.value
Next

The URL pattern starts with “http://”always. Hence we need to hardcode it. Now the remaining pattern starts with \w that matches with [a-z A-Z 0-9]i.e then alphanumeric characters .

The second component is [\W-] that matches with any alphanumeric characters with a dash so if the URL is having a dash in between ,the code will be able to determine .

*is used for repetition.

Execute Method

Execute method searches a specific string and return matches as collection.

Syntax-

object.Execute(stringPattern)

Example

Dim myReg,myString,myCol,matchFound 
Set myReg=New RegExp
myReg.Global=True
myReg.Pattern="http://(\w+[\w-]*\w+\.)*\w+"
myString="http://www.google.com"
myString=myString&VBcrlf & "http://www.bing.com"
myString=myString&VBcrlf & "http://www.altavista.com"
Set myCol=myReg.Execute(myString)
For Each matchFound in myCol
   msgbox "Found valid URL" & matchFound.value
Next

If the Execute method does not have matched content, in that case also ,execute return a collection.It will be an empty collection.

Replace Method

Replace method searches and replaces a string specified with the search string .

Syntax-

object replace (String to search,string to replace)

Back referencing

Back referencing is a technique that allows us to stare some part of the string in the buffer(temporary). It is done with the help of a parentheses.We can override the saved part of the string with other regular expressions(“?:”,”?=”,”?!”)

Example

Dim MyReg,Mystring
Set MyReg=New RegExp
MyReg.Pattern="(\s+)\s+(\s+)\s+(\s+)\s+(\s+)\s+(\s+)"
MyString=This is not so cool”
Msgbox MyReg.Replace(s,$1,$2,$4,$5)

Op->This is so cool

Test Method

Test method searches a string by executing a regular expression.It returns Boolean –true to indicate the pattern is found and false –to indicate that the pattern is not found.

Syntax –

object.test (searchString)

Example

Dim MyRag,MyString
Set MyReg=New RegExp
MyReg.IgnoreCase=TRUE
MyReg.Pattern="http://(\W+[\W-]*\W+\-)*\W+"
MyString="My favourite search engine http://www.google.com"
If MyReg.Test(MyString)then
Msgbox "the string is having an URL"
Else
Msgbox "The string does not have a valid URL"
End If

O/P ->The string is having an URL

The Matches Collection

This matches collection is a placeholders for match objects.Execute method returns this collection.If execute method is executed we get zero or more match objects in the collection.The below properties can be extracted from match object

• The string
• The length of the string
• The index value where the match is found

Note

We need to enable Global property to true to match in the whole string.Match support two properties

• Count-It returns the number of items present in the collection.
• Item-It returns the exact item based or the query on the list with a key as Index .

Match object periods three read only properties-

• First Index
• Length
• Value

The details are as follows

• First Index-returns the position where the match happens with a giving string.

Syntax-Object.FirstIndex

• Length-returns the length of a match in the search string.

Syntax-Object.Length

• Value- returns the value or text or string of a match found in a search string.

Syntax-Object.value

How to validate a phone number?(XXX)XXXX-(XXX)

Dim myReg,MyNumber
Set myReg=New RegExp
MyReg.pattern='\([0-9]{3}\[0-9]{4}-(0-9){3}
MyReg.Global=True
MyReg.Ignorecase=True
MyNumber=Inputbox("Enter your mobile in (xxx)xxxx-xxx format")
If MyReg.test(MyNumber)then 
msgbox "It is a valid mobile number"
Else
msgbox "It is not a valid mobile number"
End if

How to find the white space?

The Syntax –”^[\t]*$”

• ^ matches the start of the line.
• [\t] matches tab character for finding space or more space characters.
• $ Matches end of the line.

Dim MyReg,MyString,objMatch,spaceMatch,sMsg
Set MyReg=New RegExp
MyReg.Global=True
MyReg.pattern="^[\t]*$"
Mystring="I have a big cat"
Set spaceMatch=MyReg.Execute(Mystring)
SMsg=""
For Each objMatch in spaceMatch
sMsg="Space found at position"
objMatch.FirstIndexNumber
msgbox sMsg
Next

6.String Manipulation using Regular Expression

Making Global property True

specific match or using \b switch

Dim reg, strString
Set reg=New RegExp
reg.Pattern="/b of" //(/b matches the exact word)
reg.Global=True
strString="To take of is not easy of the ground. It needs a great offline practice."
msgbox reg.Replace(strString,"off")

As the Global property is true , it matches with all words in the string.

Making Global property False

Dim reg, strString
Set reg=New RegExp
reg.Pattern="/b of" //(/b matches the exact word)
reg.Global=False
strString="To take of is not easy of the ground. It needs a great off line practice."
msgbox reg.Replace(strString,"off")

O/P—>to take off is not easy of the ground.It needs a great off line practice. Only changes the first occurrence.

Regular Expression cheat seat:

The below patterns can be used with VBScript RegExp Object.