copy fixed content between two delimeter in visual basic - vb.net

Question

i want to copy or transfer the fixed words between two delimiting symbols from one textbox to another.i was successful in transferring the single word from one text box to another but when i wanted to transfer two or more word,it showed the error.the transferring of the word happens when the button is pressed.
My code for transferring single word between the delimiting symbol is:-
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim sSource As String = TextBox1.Text 'String that is being searched
Dim sDelimStart As String = "FirstName=" 'First delimiting word
Dim sDelimEnd As String = "." 'Second delimiting word
Dim nIndexStart As Integer = sSource.IndexOf(sDelimStart) 'Find the first occurrence of f1
Dim nIndexEnd As Integer = sSource.IndexOf(sDelimEnd) 'Find the first occurrence of f2
If nIndexStart > -1 AndAlso nIndexEnd > -1 Then '-1 means the word was not found.
Dim res As String = Strings.Mid(sSource, nIndexStart + sDelimStart.Length + 1, nIndexEnd - nIndexStart - sDelimStart.Length) 'Crop the text between
TextBox2.Text = res 'Display
End If
End Sub
Above code works properly but when when i wanted to search and transfer two words it showed the error as ArgumentException was Unhandled and Argument 'Length' must be greater or equal to zero.My error containg code is:
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim sSource As String = TextBox1.Text 'String that is being searched
Dim sSource1 As String = TextBox1.Text
Dim sDelimStart As String = "FirstName=" 'First delimiting word
Dim sDelimStart1 As String = "LastName="
Dim sDelimEnd As String = "." 'Second delimiting word
Dim sDelimEnd1 As String = "."
Dim nIndexStart As Integer = sSource.IndexOf(sDelimStart) 'Find the first occurrence of f1
Dim nIndexStart1 As Integer = sSource1.IndexOf(sDelimStart1)
Dim nIndexEnd As Integer = sSource.IndexOf(sDelimEnd) 'Find the first occurrence of f2
Dim nIndexEnd1 As Integer = sSource1.IndexOf(sDelimEnd1)
If nIndexStart > -1 AndAlso nIndexEnd > -1 Then '-1 means the word was not found.
Dim res As String = Strings.Mid(sSource, nIndexStart + sDelimStart + 1, nIndexEnd - nIndexStart - sDelimStart.Length) 'Crop the text between
TextBox2.Text = res 'Display
End If
If nIndexStart1 > -1 AndAlso nIndexEnd1 > -1 Then '-1 means the word was not found.
Dim res1 As String = Strings.Mid(sSource1, nIndexStart1 + sDelimStart1 + 1, nIndexEnd1 - nIndexStart1 - sDelimStart1.Length) 'Crop the text between
TextBox3.Text = res1 'Display
End If
End Sub
I think the error is due to the repeated use of Length variable in 'if' statement but i don't know how to fix that.The link to the snapshot of my desired output is:http://tinypic.com/r/1zy7iwz/8 i was only able to transfer the word harry but not the porter.Any help is much appreciated.

Answer 1

To start, I think you need to add .length after your sDelimStart and sDelimStart1. Currently, you're trying to pass a String + Integer as an Integer.
Dim res As String = Strings.Mid(sSource, nIndexStart + sDelimStart.length + 1, nIndexEnd - nIndexStart - sDelimStart.Length)
And in your second if statement:
Dim res1 As String = Strings.Mid(sSource1, nIndexStart1 + sDelimStart1.length + 1, nIndexEnd1 - nIndexStart1 - sDelimStart1.Length)
However, I would recommend using the String.Split function:
https://msdn.microsoft.com/en-us/library/b873y76a%28v=vs.110%29.aspx
EDIT: Why it is displaying same thing in both.
I think this is because you need to find the last index of the delimiters.
Dim nIndexStart As Integer = sSource.IndexOf(sDelimStart) 'Find the first occurrence of f1
Dim nIndexStart1 As Integer = sSource1.LastIndexOf(sDelimStart1)
Dim nIndexEnd As Integer = sSource.IndexOf(sDelimEnd) 'Find the first occurrence of f2
Dim nIndexEnd1 As Integer = sSource1.LastIndexOf(sDelimEnd1)