How vb.net split string - vb.net

Question

I have a file txt file that values i want split after value "accession_number=" and before value "&token"
example Values in text file :
10.0.0.6:80/ImageSuite/Web/Worklist/DICOMViewer.aspx?patient_id=5049885&study_uid=201702060824&accession_number=20170206082802&token
10.0.0.6:80/ImageSuite/Web/Worklist/DICOMViewer.aspx?patient_id=4409276&study_uid=201702060826&accession_number=20170206083002&token
10.0.0.6:80/ImageSuite/Web/Worklist/DICOMViewer.aspx?patient_id=4402764&study_uid=201702060801&accession_number=20170206080416&token
10.0.0.6:80/ImageSuite/Web/Worklist/DICOMViewer.aspx?patient_id=4402537&study_uid=201702060837&accession_number=20170206084025&token
example values after proccess :
20170206082802
20170206083002
20170206080416
20170206084025
Thank you

Answer 1

You can read each line into an array of strings using File.ReadAllLines() and then iterate over that and parse the information using a Regex.
'Declare the Regex.
Dim Parser As New Regex("(?<=accession_number\=)\d+", RegexOptions.IgnoreCase)
'Read the file's lines into an array of strings.
Dim Lines As String() = File.ReadAllLines("C:\test.txt")
'Iterate over the array.
For Each Line As String In Lines
Dim m As Match = Parser.Match(Line) 'Match the pattern.
If m.Success = True Then 'Was the match successful?
Console.WriteLine(m.Value) 'Print the matched value.
End If
Next
Online test: http://ideone.com/VU5Iyj
Regex pattern explanation:
(?<=accession_number\=)\d+
(?<= => Match must be preceded by...
accession_number\= => ..."accession_number=".
) => End of preceding capture group.
\d+ => Match one or more numerical characters.

Answer 2

You can do it by reading all lines, and then based on the lines you can execute following code (assuming the file you want to read is located at C:\test.txt)
dim results = from line in File.ReadAllLines("C:\test.txt") _
where not String.IsNullOrWhiteSpace(line) _
from field in line.Split("&") _
where field.StartsWith("accession_number=") _
select field.Split("=")(1)
for each result in results
Console.WriteLine(result)
next
This will use as an input all lines, and then for the lines that are not empty, it will split using & and then it checks if that field startswith the accession_number, if it does, it splits by = to return the second item in the array.
As an extra explanation:
from line in File.ReadAllLines("C:\test.txt")
while evaluate every single line in the file
' input eg: 10.0.0.6:80/ImageSuite/Web/Worklist/DICOMViewer.aspx?patient_id=5049885&study_uid=201702060824&accession_number=20170206082802&token
where not String.IsNullOrWhiteSpace( line )
will exclude all empty lines (or lines that exist only of whitespaces)
from field in line.Split("&")
will split every found line into an array of strings using the & as a separator
' field eg: accession_number=20170206082802
where field.StartsWith("accession_number=")
will exclude all fields that do not start with accession_number=
select field.Split("=")(1)
' result sample: 20170206082802
will return for any matches the part after =
A full example you can find on this dotnetfiddle. It uses a slightly different method to read from stream, simply because in that environment, I cannot provide a dummy file, however, it should do the trick