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Regular Expression Help

gr8life
gr8life asked
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Last Modified: 2010-04-23
I need help adding the regular expression to the Regex line to find the value “Not in Database” and error checking.  Columns 5 and 8 are where the information may be located.  Also the file is VbTab delimited.

Here is what I have so far:

Imports System.IO
Imports System.Text.RegularExpressions

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Try
                  Dim re As New Regex( )

              Dim input As String
              Dim output As String
              Dim sr As New StreamReader("C:\resource\input.txt")
 
              input = sr.ReadToEnd()
               sr.Close()


             If input <> output Then
                 Dim sw As New StreamWriter("C:\resource\NIDB.txt")
                 sw.Write(output)
                 sw.Close()
            End If


Thanks for your time and expertise,
Gr8life
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I know this isnt regex, but with tabdelim, this seems easier. I am also assuming there is more than one line of values to evaluate.  If you are needing to use RegEx, I am sure someone will chime in soon.

Dim sr As New StreamReader("C:\resource\input.txt")
dim newLine as string
do until sr.peek = -1
newline = sr.readline()
             Dim DataFieldData() As String =  newLine.Split(ControlChars.Tab)
              Dim input As String = DataFieldData(4)
              Dim output As String = DataFieldData(7)
             
'code to evaluate/write goes here
loop
sr.Close()
     

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Fernando SotoRetired
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Distinguished Expert 2017

Commented:
Hi gr8life;
Not sure what you want. In your statement 'find the value "Not in Database” and error checking'. Does this mean that if column 5 has a value it will contain the phrase "Not in Database” and if column 5 has this phrase in it does that mean that you want the value in column then?

Can this happen on multiple lines in the file?

You define two string variables:

              Dim input As String
              Dim output As String

you assign a value to input and later on in the code you compare it to output but you never assign a value to output?

Let me know I would be glad to help with a Regex pattern.

Fernando

Author

Commented:
After reading the reply from razorback041, I was wondering if his approach is more efficient to process large data sets up to 2 gig in size?

The "Not in Database" value can occur on multiple lines, twice on one line, or not on any line.

Sample data:

cat      cat      cat      Not in Database      cat      cat      Not in Database      cat
dog      dog      dog      Not in Database      dog      dog      dog                  dog
rat      rat      rat      rat                  rat      rat      rat                  rat

I added extra tabs to illustrate the columns better.  Also the input file has more columns than I have posted here.

The error check I was referring to is if the document doesn’t have any occurrences of “Not in Database” then message box, No Matches.

Thank you for taking the time to read this post,
Gr8life
Fernando SotoRetired
CERTIFIED EXPERT
Distinguished Expert 2017

Commented:
Hi gr8life;

The following code will read the input data into the variable input. search the input for "Not in Database" with the Regex object. Then writes all the lines that have the phrase in the line to a file.

Imports System.Text.RegularExpressions
Imports System.IO

        Dim re As New Regex("^.*?Not\sin\sDatabase.*?$", RegexOptions.Multiline)
        Dim sr As New StreamReader("C:\resource\input.txt")
        Dim input As String = sr.ReadToEnd()
        sr.Close()
        Dim mc As MatchCollection
        Dim sw As New StreamWriter("C:\resource\input_NotInDB.txt")

        mc = re.Matches(input)
        For Each m As Match In mc
            ' If you have any matches in the input data the whole line that it
            ' appears in will be one of the matches from the match collection.
            sw.Write(m.Value)
        Next
        sw.Close()


Fernando

Author

Commented:
FernandoSoto, I tried the code you posted and I works great however it writes all the data to one line.  Is there a way to write the data into several lines like this:

cat     cat     cat     Not in Database     cat     cat     Not in Database     cat
dog     dog     dog     Not in Database     dog     dog     dog               dog

instead of:
cat     cat     cat     Not in Database     cat     cat     Not in Database     cat dog     dog     dog     Not in Database     dog     dog     dog               dog

Thanks for your time,
Gr8life
Retired
CERTIFIED EXPERT
Distinguished Expert 2017
Commented:
Hi gr8life;

When you created the Regex object did you write it as I did:

        Dim re As New Regex("^.*?Not\sin\sDatabase.*?$", RegexOptions.Multiline)

Because the ^ in the Regex pattern marks the begining of a line and the $ marks the end of a line as long as the RegexOptions.Multiline is in the statement as above.

The other thing is that the file is one continus line with no CrLf characters at the end of each line.

But if you did the above and it is still comming out as one line then you can try this. Use the WriteLine in place of the Write.

            sw.WriteLine(m.Value)

Fernando
Fernando SotoRetired
CERTIFIED EXPERT
Distinguished Expert 2017

Commented:
In fact the way the pattern is set up if you do not have the RegexOptions.Multiline in the creation of the Regex object it will take the whole input as only one line.

Author

Commented:
It works great!

Thank you very much,
Gr8life
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