Regular Expression in QTP

Regular Expression in QTP – Object Properties and Methods

The Regular Expression object provides simple regular expression support.

Properties

  1. Global Property
  2. IgnoreCase Property
  3. Pattern Property

Methods

  1. Execute Method
  2. Replace Method
  3. Test Method

Let us see in detaila bout each of these Properties and Methods.

1.Global Property

Sets or returns a Boolean value that indicates if a pattern should match all occurrences in an entire search string or just the first one.

object.Global [= True | False ]

The object argument is always a RegExp object. The value of the Global property is True if the search applies to the entire string, False if it does not. Default is False.

Remarks

The following code illustrates the use of the Global property (change the value assigned to Global property to see its effect):

Function RegExpTest(patrn, strng)
   Dim regEx, Match, Matches   ' Create variable.
   Set regEx = New RegExp   ' Create a regular expression.
   regEx.Pattern = patrn   ' Set pattern.
   regEx.IgnoreCase = True   ' Set case insensitivity.
   regEx.Global = True   ' Set global applicability.
   Set Matches = regEx.Execute(strng)   ' Execute search.
   For Each Match in Matches   ' Iterate Matches collection.
      RetStr = RetStr & "Match found at position "
      RetStr = RetStr & Match.FirstIndex & ". Match Value is '"
      RetStr = RetStr & Match.Value & "'." & vbCRLF
   Next
   RegExpTest = RetStr
End Function
MsgBox(RegExpTest("is.", "IS1 is2 IS3 is4"))

 

2.IgnoreCase Property

Sets or returns a Boolean value that indicates if a pattern search is case-sensitive or not.

object.IgnoreCase [= True | False ]

The object argument is always a RegExp object. The value of the IgnoreCase property is False if the search is case-sensitive, True if it is not. Default is False.

Remarks

The following code illustrates the use of the IgnoreCase property (change the value assigned to IgnoreCase property to see its effect):

Function RegExpTest(patrn, strng)
   Dim regEx, Match, Matches   ' Create variable.
   Set regEx = New RegExp   ' Create a regular expression.
   regEx.Pattern = patrn   ' Set pattern.
   regEx.IgnoreCase = True   ' Set case insensitivity.
   regEx.Global = True   ' Set global applicability.
   Set Matches = regEx.Execute(strng)   ' Execute search.
   For Each Match in Matches   ' Iterate Matches collection.
      RetStr = RetStr & "Match found at position "
      RetStr = RetStr & Match.FirstIndex & ". Match Value is '"
      RetStr = RetStr & Match.Value & "'." & vbCRLF
   Next
   RegExpTest = RetStr
End Function
MsgBox(RegExpTest("is.", "IS1 is2 IS3 is4"))

 

3.Pattern Property

Sets or returns the regular expression pattern being searched for.

object.Pattern [= “searchstring“]

Arguments

object

Required. Always a RegExp object variable.

searchstring

Optional. Regular string expression being searched for. May include any of the regular expression characters defined in the table in the Settings section.

Settings

Special characters and sequences are used in writing patterns for regular expressions. The following table describes and gives an example of the characters and sequences that can be used.

Character

Description

Marks the next character as either a special character or a literal. For example, “n” matches the character “n”. “n” matches a newline character. The sequence “\” matches “” and “(” matches “(“.

^

Matches the beginning of input.

$

Matches the end of input.

*

Matches the preceding character zero or more times. For example, “zo*” matches either “z” or “zoo”.

+

Matches the preceding character one or more times. For example, “zo+” matches “zoo” but not “z”.

?

Matches the preceding character zero or one time. For example, “a?ve?” matches the “ve” in “never”.

.

Matches any single character except a newline character.

(pattern)

Matches pattern and remembers the match. The matched substring can be retrieved from the resulting Matches collection, using Item [0]…[n]. To match parentheses characters ( ), use “(” or “)”.

x|y

Matches either x or y. For example, “z|wood” matches “z” or “wood”. “(z|w)oo” matches “zoo” or “wood”.

{n}

n is a nonnegative integer. Matches exactly n times. For example, “o{2}” does not match the “o” in “Bob,” but matches the first two o’s in “foooood”.

{n,}

n is a nonnegative integer. Matches at least n times. For example, “o{2,}” does not match the “o” in “Bob” and matches all the o’s in “foooood.” “o{1,}” is equivalent to “o+”. “o{0,}” is equivalent to “o*”.

{n,m}

m and n are nonnegative integers. Matches at least n and at most m times. For example, “o{1,3}” matches the first three o’s in “fooooood.” “o{0,1}” is equivalent to “o?”.

[xyz]

A character set. Matches any one of the enclosed characters. For example, “[abc]” matches the “a” in “plain”.

[^xyz]

A negative character set. Matches any character not enclosed. For example, “[^abc]” matches the “p” in “plain”.

[a-z]

A range of characters. Matches any character in the specified range. For example, “[a-z]” matches any lowercase alphabetic character in the range “a” through “z”.

[^m-z]

A negative range characters. Matches any character not in the specified range. For example, “[m-z]” matches any character not in the range “m” through “z”.

b

Matches a word boundary, that is, the position between a word and a space. For example, “erb” matches the “er” in “never” but not the “er” in “verb”.

B

Matches a non-word boundary. “ea*rB” matches the “ear” in “never early”.

d

Matches a digit character. Equivalent to [0-9].

D

Matches a non-digit character. Equivalent to [^0-9].

f

Matches a form-feed character.

n

Matches a newline character.

r

Matches a carriage return character.

s

Matches any white space including space, tab, form-feed, etc. Equivalent to “[ fnrtv]”.

S

Matches any nonwhite space character. Equivalent to “[^ fnrtv]”.

t

Matches a tab character.

v

Matches a vertical tab character.

w

Matches any word character including underscore. Equivalent to “[A-Za-z0-9_]”.

W

Matches any non-word character. Equivalent to “[^A-Za-z0-9_]”.

num

Matches num, where num is a positive integer. A reference back to remembered matches. For example, “(.)1″ matches two consecutive identical characters.

n

Matches n, where n is an octal escape value. Octal escape values must be 1, 2, or 3 digits long. For example, “11” and “11″ both match a tab character. “011″ is the equivalent of “01″ & “1”. Octal escape values must not exceed 256. If they do, only the first two digits comprise the expression. Allows ASCII codes to be used in regular expressions.

xn

Matches n, where n is a hexadecimal escape value. Hexadecimal escape values must be exactly two digits long. For example, “x41″ matches “A”. “x041″ is equivalent to “x04″ & “1”. Allows ASCII codes to be used in regular expressions.

Remarks

The following code illustrates the use of the Pattern property.

Function RegExpTest(patrn, strng)

   Dim regEx, Match, Matches   ‘ Create variable.

   Set regEx = New RegExp   ‘ Create a regular expression.

   regEx.Pattern = patrn   ‘ Set pattern.

   regEx.IgnoreCase = True   ‘ Set case insensitivity.

   regEx.Global = True   ‘ Set global applicability.

   Set Matches = regEx.Execute(strng)   ‘ Execute search.

   For Each Match in Matches   ‘ Iterate Matches collection.

      RetStr = RetStr & “Match found at position “

      RetStr = RetStr & Match.FirstIndex & “. Match Value is ‘”

      RetStr = RetStr & Match.Value & “‘.” & vbCRLF

   Next

   RegExpTest = RetStr

End Function

MsgBox(RegExpTest(“is.”, “IS1 is2 IS3 is4″))

 

1.Execute Method

Executes a regular expression search against a specified string.

object.Execute(string)

Arguments

object

Required. Always the name of a RegExp object.

string

Required. The text string upon which the regular expression is executed.

Remarks

The actual pattern for the regular expression search is set using the Pattern property of the RegExp object.

The Execute method returns a Matches collection containing a Match object for each match found in string. Execute returns an empty Matches collection if no match is found.

The following code illustrates the use of the Execute method.

Function RegExpTest(patrn, strng)

  Dim regEx, Match, Matches      ‘ Create variable.

  Set regEx = New RegExp         ‘ Create a regular expression.

  regEx.Pattern = patrn         ‘ Set pattern.

  regEx.IgnoreCase = True         ‘ Set case insensitivity.

  regEx.Global = True         ‘ Set global applicability.

  Set Matches = regEx.Execute(strng)   ‘ Execute search.

  For Each Match in Matches      ‘ Iterate Matches collection.

    RetStr = RetStr & “Match found at position “

    RetStr = RetStr & Match.FirstIndex & “. Match Value is ‘”

    RetStr = RetStr & Match.Value & “‘.” & vbCRLF

  Next

  RegExpTest = RetStr

End Function

MsgBox(RegExpTest(“is.”, “IS1 is2 IS3 is4″))

 

2.Replace Method

Replaces text found in a regular expression search.

object.Replace(string1, string2)

Arguments

object

Required. Always the name of a RegExp object.

string1

Required. String1 is the text string in which the text replacement is to occur.

string2

Required. String2 is the replacement text string.

Remarks

The actual pattern for the text being replaced is set using the Pattern property of the RegExp object.

The Replace method returns a copy of string1 with the text of RegExp.Pattern replaced with string2. If no match is found, a copy of string1 is returned unchanged.

The following code illustrates use of the Replace method.

Function ReplaceTest(patrn, replStr)

  Dim regEx, str1               ‘ Create variables.

  str1 = “The quick brown fox jumped over the lazy dog.”

  Set regEx = New RegExp            ‘ Create regular expression.

  regEx.Pattern = patrn            ‘ Set pattern.

  regEx.IgnoreCase = True            ‘ Make case insensitive.

  ReplaceTest = regEx.Replace(str1, replStr)   ‘ Make replacement.

End Function

 

MsgBox(ReplaceTest(“fox”, “cat”))      ‘ Replace ‘fox’ with ‘cat’.

In addition, the Replace method can replace subexpressions in the pattern. The following call to the function shown in the previous example swaps each pair of words in the original string:

MsgBox(ReplaceText(“(S+)(s+)(S+)”, “$3$2$1″))   ‘ Swap pairs of words.

 

3.Test Method

Executes a regular expression search against a specified string and returns a Boolean value that indicates if a pattern match was found.

object.Test(string)

Arguments

object

Required. Always the name of a RegExp object.

string

Required. The text string upon which the regular expression is executed.

Remarks

The actual pattern for the regular expression search is set using the Pattern property of the RegExp object. The RegExp.Global property has no effect on the Test method.

The Test method returns True if a pattern match is found; False if no match is found.

The following code illustrates the use of the Test method.

Function RegExpTest(patrn, strng)

  Dim regEx, retVal            ‘ Create variable.

  Set regEx = New RegExp         ‘ Create regular expression.

  regEx.Pattern = patrn         ‘ Set pattern.

  regEx.IgnoreCase = False      ‘ Set case sensitivity.

  retVal = regEx.Test(strng)      ‘ Execute the search test.

  If retVal Then

    RegExpTest = “One or more matches were found.”

  Else

    RegExpTest = “No match was found.”

  End If

End Function

MsgBox(RegExpTest(“is.”, “IS1 is2 IS3 is4″))

 

Match Object

Provides access to the read-only properties of a regular expression match.

A Match object can be only created using the Execute method of the RegExp object, which actually returns a collection of Match objects. All Match object properties are read-only.

When a regular expression is executed, zero or more Match objects can result. Each Match object provides access to the string found by the regular expression, the length of the string, and an index to where the match was found.

The following code illustrates the use of the Match object:

Function RegExpTest(patrn, strng)
   Dim regEx, Match, Matches   ' Create variable.
   Set regEx = New RegExp   ' Create regular expression.
   regEx.Pattern = patrn   ' Set pattern.
   regEx.IgnoreCase = True   ' Set case insensitivity.
   regEx.Global = True   ' Set global applicability.
   Set Matches = regEx.Execute(strng)   ' Execute search.
   For Each Match in Matches   ' Iterate Matches collection.
      RetStr = RetStr & "Match " & I & " found at position "
      RetStr = RetStr & Match.FirstIndex & ". Match Value is "'
      RetStr = RetStr & Match.Value & "'." & vbCRLF
   Next
   RegExpTest = RetStr
End Function
MsgBox(RegExpTest("is.", "IS1 is2 IS3 is4"))

 

Matches Collection

Collection of regular expression Match objects.

A Matches collection contains individual Match objects, and can be only created using the Execute method of the RegExp object. The Matches collection’s one property is read-only, as are the individual Match object properties.

When a regular expression is executed, zero or more Match objects can result. Each Match object provides access to the string found by the regular expression, the length of the string, and an index to where the match was found.

The following code illustrates how to obtain a Matches collection from a regular expression search and how to iterate the collection:

Function RegExpTest(patrn, strng)
   Dim regEx, Match, Matches   ' Create variable.
   Set regEx = New RegExp   ' Create regular expression.
   regEx.Pattern = patrn   ' Set pattern.
   regEx.IgnoreCase = True   ' Set case insensitivity.
   regEx.Global = True   ' Set global applicability.
   Set Matches = regEx.Execute(strng)   ' Execute search.
   For Each Match in Matches   ' Iterate Matches collection.
      RetStr = RetStr & "Match found at position "
      RetStr = RetStr & Match.FirstIndex & ". Match Value is '"
      RetStr = RetStr & Match.Value & "'." & vbCRLF
   Next
   RegExpTest = RetStr
End Function
MsgBox(RegExpTest("is.", "IS1 is2 IS3 is4"))

 

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