I'm working on a VB.Net application that needs to do quite a bit of string
pattern matching, and am having problems using the "LIKE" operator to match
the same string twice in the pattern. For example, in the following code:
Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click
Dim theString As String
theString = "1234 TEST 5432 TEST ABCD"
If theString Like "*TEST*TEST *" Then
MessageBox.Show ("Matches!")
Else
MessageBox.Show ("No Match!")
End If
End Sub
I would expect the LIKE operator in this test to return true, since
theString matches the pattern "*TEST*TEST *", specifying zero-or-more
characters followed by "TEST" followed by zero-or-more characters followed
by "TEST" followed by zero-or-more characters. However, when I run the above
code, the LIKE operator returns false. If I change the pattern to
"*TEST*ABC* ", the LIKE operator returns true. If I alter the pattern to
something like "*TEST*TEST A*", it again returns false. It seems that LIKE
won't match a pattern that contains the same string of characters twice. Can
anyone explain why the operator behaves this way?
Thanks in advance for any replies. 2 6007
Ed,
I cannot explain the Like operator as I don't use it very much, I use the
System.Test.Reg ularExpressions .RegEx class instead. As the patterns
supported by RegEx far exceeds the patterns allowed in the Like operator.
Something like:
Dim theRegex As New
System.Text.Reg ularExpressions .Regex(".*TEST. *TEST.*")
Dim theString As String
theString = "1234 TEST 5432 TEST ABCD"
If theRegex.IsMatc h(theString) Then
MessageBox.Show ("Matches!")
Else
MessageBox.Show ("No Match!")
End If
I will normally define my Regex variables as Shared within a class, or
Static within a routine, with the RegExOptions.Co mpiled option if the regex
is used a lot within my program.
Something like:
Imports System.Text.Reg ularExpressions
Static theRegex As New Regex(".*TEST.* TEST.*",
RegexOptions.Co mpiled)
The following site provides a good overview of regular expressions: http://www.regular-expressions.info/
While this site provides the syntax specifically supported by .NET: http://msdn.microsoft.com/library/de...geElements.asp
Hope this helps
Jay
"Ed Brown" <eb****@compute r-systems.com> wrote in message
news:e7******** *****@TK2MSFTNG P09.phx.gbl... I'm working on a VB.Net application that needs to do quite a bit of string pattern matching, and am having problems using the "LIKE" operator to match the same string twice in the pattern. For example, in the following code:
Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As System.EventArg s) Handles Button1.Click Dim theString As String theString = "1234 TEST 5432 TEST ABCD" If theString Like "*TEST*TEST *" Then MessageBox.Show ("Matches!") Else MessageBox.Show ("No Match!") End If End Sub
I would expect the LIKE operator in this test to return true, since theString matches the pattern "*TEST*TEST *", specifying zero-or-more characters followed by "TEST" followed by zero-or-more characters followed by "TEST" followed by zero-or-more characters. However, when I run the above code, the LIKE operator returns false. If I change the pattern to "*TEST*ABC* ", the LIKE operator returns true. If I alter the pattern to something like "*TEST*TEST A*", it again returns false. It seems that LIKE won't match a pattern that contains the same string of characters twice. Can anyone explain why the operator behaves this way?
Thanks in advance for any replies.
Thanks Jay, using the RegEx class did the trick.
"Jay B. Harlow [MVP - Outlook]" <Ja************ @msn.com> wrote in message
news:up******** ******@TK2MSFTN GP15.phx.gbl... Ed, I cannot explain the Like operator as I don't use it very much, I use the System.Test.Reg ularExpressions .RegEx class instead. As the patterns supported by RegEx far exceeds the patterns allowed in the Like operator.
Something like:
Dim theRegex As New System.Text.Reg ularExpressions .Regex(".*TEST. *TEST.*") Dim theString As String theString = "1234 TEST 5432 TEST ABCD" If theRegex.IsMatc h(theString) Then MessageBox.Show ("Matches!") Else MessageBox.Show ("No Match!") End If
I will normally define my Regex variables as Shared within a class, or Static within a routine, with the RegExOptions.Co mpiled option if the regex is used a lot within my program.
Something like:
Imports System.Text.Reg ularExpressions
Static theRegex As New Regex(".*TEST.* TEST.*", RegexOptions.Co mpiled)
The following site provides a good overview of regular expressions:
http://www.regular-expressions.info/
While this site provides the syntax specifically supported by .NET:
http://msdn.microsoft.com/library/de...geElements.asp
Hope this helps Jay
"Ed Brown" <eb****@compute r-systems.com> wrote in message news:e7******** *****@TK2MSFTNG P09.phx.gbl... I'm working on a VB.Net application that needs to do quite a bit of string pattern matching, and am having problems using the "LIKE" operator to match the same string twice in the pattern. For example, in the following code:
Private Sub Button1_Click(B yVal sender As System.Object, ByVal e As System.EventArg s) Handles Button1.Click Dim theString As String theString = "1234 TEST 5432 TEST ABCD" If theString Like "*TEST*TEST *" Then MessageBox.Show ("Matches!") Else MessageBox.Show ("No Match!") End If End Sub
I would expect the LIKE operator in this test to return true, since theString matches the pattern "*TEST*TEST *", specifying zero-or-more characters followed by "TEST" followed by zero-or-more characters followed by "TEST" followed by zero-or-more characters. However, when I run the above code, the LIKE operator returns false. If I change the pattern to "*TEST*ABC* ", the LIKE operator returns true. If I alter the pattern to something like "*TEST*TEST A*", it again returns false. It seems that LIKE won't match a pattern that contains the same string of characters twice. Can anyone explain why the operator behaves this way?
Thanks in advance for any replies.
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