VBSCRIPT Parse Large file into smaller files based on header info

Posted on 2009-04-08
Last Modified: 2012-05-06
I need help creating a script that will read a large file that contains multiple records (no CR/LF) and, based on a known header ("1MHG"),  will create individual files.  The records can be long so I'm not sure using arrays will work.
Example: the file "ALL.TXT" contains 45 records in one long string. They all start with the header info "1MHG". Knowing that, we can find the start of the next record, because it will also start with "1MHG".  We do not know how the record ends.  I need to be able to strip each record, from the beginning of the "1MHG" occurance to the next occurance, and write 45 files. Each file will be named sequentially (file1,txt, file2.txt, etc). I have the code that opens the file and creates the output and names them sequentially. I just cannot get the part that parses the string and strips out the records.
Question by:mannyms
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LVL 25

Accepted Solution

kevp75 earned 500 total points
ID: 24106205
post your code?

basically what you'd be looking to do is a split on the string, and then loop through the array created.  So long as your machine doesn't have only 256M of RAM you should be all set with this method ;)

strVar = Split(objFile.ReadAll, "1MHG")
If IsArray(strVar) Then
     For i = 0 To Ubound(strVar) - 1
         set blah = blahblah.CreateTextFile(named....txt)
         set blah = Nothing
      Next : i = Null
End If

(this is untested code, and the variables are unknow...please change what is necessary)
LVL 25

Expert Comment

ID: 24106222
is the header for the files always on the same line?   You can read in the first line for the value of the split...

Author Comment

ID: 24106813
The file is one Loooooong physical record with multiple logical records embedded, but they always start with the string "1MHG". They can be really large as well. My test file has only 45 records but is 1MB. We are expecting files that could potentially contain 100s if not 1000s or logical records. So the importance of doing this optimally is important.  
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LVL 25

Expert Comment

ID: 24107313
can you post your existing code?   Let's see if we can modify it to handle this.

Take out (or x out) anything incriminating :)

Author Comment

ID: 24108119
This is working well except that the "1MHG" is being stripped out of the array.

Dim objFSO, objFolder, objShell, objInputFile, objOutput, objFile, count_r
Dim strDirectory, strInputFile, strOutputFile
count_r = 1
tmpDate = Format(Date, "mmddyy")
tmpTime = Format(Time, "hhmmss")
'---determine actual input/output locations later---
strInputFile = "c:\all.al3"
strDirectory = "c:\AL3_" & tmpDate & tmpTime
strOutputFile = "\file" & count_r & ".al3"
Set objFSO = CreateObject("Scripting.FileSystemObject")
If objFSO.FolderExists(strDirectory) Then
   Set objFolder = objFSO.GetFolder(strDirectory)
   Set objFolder = objFSO.CreateFolder(strDirectory)
End If
Set objInputFile = Nothing
Set objOutputFile = Nothing
Set objFolder = Nothing
Const ForAppending = 8, ForReading = 1, ForWriting = 2
Set objInputFile = objFSO.OpenTextFile(strInputFile, ForReading)
strVar = Split(objInputFile.ReadAll, "1MHG")
If IsArray(strVar) Then
     For i = 1 To UBound(strVar)
        strOutputFile = "\file" & count_r & ".al3"
        If objFSO.FileExists(strDirectory & strOutputFile) Then
            '----add code = delete the file and recreate it.
            Set objFolder = objFSO.GetFolder(strDirectory)
            Set objOutputFile = objFSO.CreateTextFile(strDirectory & strOutputFile)
        End If
             objOutputFile.WriteLine (strVar(i))
            Set objOutputFile = Nothing
            count_r = count_r + 1
      Next: i = Null
End If

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Author Comment

ID: 24108390
Just got updated to a spec issue:(will create separate post if needed)
within the array for each record, starting at position 69 for 6 bytes, I must replace the existing data (almost always spaces) with "AWF   ". Positions 1-68 and positions 72 thru the end (variable) are written as is.

(See code snippet for fixed length font)

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Author Closing Comment

ID: 31568181
Provided the direction needed to complete. Excellent contributor.

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