Question

How to read a string in another string where between Starting Index and first-encountered Ending Index

I have one giant file which contains info for each customers and they seperated the customers info with Starting and Ending Indexes and I need to get a specific customer info to display.

    Dim oFile As New FileInfo(sFileName)
    Dim sFileContent As String = oFile.OpenText().ReadToEnd()
    Dim iStartIndex As Integer = sFileContent.IndexOf(roNotification.StartByte)
    Dim iEndIndex As Integer = sFileContent.IndexOf(roNotification.EndByte, iStartIndex)
    Dim sCustomerInfo As String = sFileContent.Substring(iStartIndex + roNotification.StartByte.Length - 1, iEndIndex)

Nothing much tho. But it reads the file and put that giant file into sFileContent variable. I am not sure how efficient this way is (seems worse than MemoryStream).

Index strings can be more than 1 character.

Edit:

More info about the file, the file contains only one giant line and that lines contains all the info. I cannot touch on that file except for reading it since it has really confidential data.

I am looking for the string between Starting Index and First-encountered Ending Index exclusively.

Answer 1

You should read the file line-by-line:

Using reader = file.OpenText()
    Dim line As String
    While True
        line = reader.ReadLine()
        If ReferenceEquals(Line, Nothing) Then Exit While

        'Parse the line and figure out what to do with it
    End While
End Using

This way, you’ll never have more than one line in memory at a time.