vb.net: extract string from "a123" to "b123"

i have a string that looks like this:

sodjfoisdfsdf sdofij sodiosifosf fsdi a123 sdfoi sdofi osdi foi sdofd oi b123 sdfoijsfdoifsdiosfdoifso开发者_如何学Cifsdofjssfdoji

how do i extract everything from a123 to b123?

If your patterns are going to be as simple as a123 then simple string operations will suffice:

Dim s As String = "sodjfoisdfsdf sdofij sodiosifosf fsdi a123 sdfoi sdofi osdi foi sdofd oi b123 sdfoijsfdoifsdiosfdoifsoifsdofjssfdoji"

Dim startIndex As Integer = s.IndexOf("a123") + "a123".Length
Dim endIndex As Integer = s.IndexOf("b123")

Dim result = s.Substring(startIndex, endIndex - startIndex)

You can use the Text parsing functions to find the start and end position for your tokens.

For example:

Dim s As String = "sodjfoisdfsdf sdofij sodiosifosf fsdi a123 sdfoi sdofi osdi foi sdofd oi b123 sdfoijsfdoifsdiosfdoifsoifsdofjssfdoji"
Dim startToken As String = "a123"
Dim endToken As String = "b123"
Dim startTokenPosition As Integer = s.IndexOf(startToken)
Dim endTokenPosition As Integer = s.IndexOf(endToken)
'Validate both startToken and endToken were found...
Dim mysubstring As String = s.Substring(startTokenPosition + startToken.Length, endTokenPosition - startTokenPosition - startToken.Length)