vb.net 2010 code check if values exist

[dcof]

In a vb.net 2010 application, I have the following code that works sometimes:

Dim txtOrigAddress As String = _attendanceLetterOrig.Substring(CInt(_attendanceLetterOrig.IndexOf("ADDR_BEG")), _attendanceLetterOrig.IndexOf("ADDR_END") - _attendanceLetterOrig.IndexOf("ADDR_BEG"))
Dim txtOrigAddress As String = _attendanceLetterOrig.Substring(CInt(_attendanceLetterOrig.IndexOf("ADDR_NEXT")),4)

The problem is the folllowing values do not exist:
_attendanceLetterOrig.IndexOf("ADDR_BEG")
_attendanceLetterOrig.IndexOf("ADDR_END")
_attendanceLetterOrig.Substring(CInt"ADDR_NEXT")

What kind of an edit can I use to check if the 3 values listed above actually exist? I want to prevent application errors. Would you show me the code to see if the values really exist?

[Lost User]

String.IndexOf Method (String) (System)[^]

Speed of sound - 1100 ft/sec Speed of light - 186,000 mi/sec Speed of stupid - instantaneous.

[Richard Deeming]

If the substring isn't found, IndexOf returns -1. You'll need to find and store each index first, then check that they're not -1 before calling Substring. Also, IndexOf already returns an Integer. There's no need to call CInt.

Dim startIndex As Integer = _attendanceLetterOrig.IndexOf("ADDR_BEG")
Dim endIndex As Integer = _attendanceLetterOrig.IndexOf("ADDR_END", startIndex)
If startIndex <> -1 AndAlso endIndex <> -1 Then
Dim txtOrigAddress As String = _attendanceLetterOrig.Substring(startIndex, endIndex - startIndex)
End If

Your second example makes no sense. The IndexOf method returns the index of the start of the matched substring, if found. So _attendanceLetterOrig.IndexOf("ADDR_NEXT") returns the index of "A", and _attendanceLetterOrig.Substring(..., 4) will always return "ADDR".

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