How to Get the Positions of Strings Filtered by Multi-Split Method in VB.net With LINQ

Question

According to the previous question, the method of multi-splitting (Multi-Split)

I'm working on a VB.net script and need help extracting the positions of specific substrings from a given input string based on a multi-split condition. The input string is defined as follows:

Dim MultiSplit as String()={"C","B","A"}
Dim MyString As String = "00[A]1111{C}22(B)33333{C}4{C}5{C}666[A]777(B)8(B)99{C}999[A]101010" 

The expected output is a string array containing the positions of each occurrence of the substrings. For example, for MultiSplit containing {"C", "B", "A"}, the expected output for positions is:

Dim ResultOfPositions as String()={"32-36","38-42"}.

• For {"A", "B", "C"}, the result should be Dim ResultOfPositions as String()={"4-9","11-14","16-22","24-26","28-30","31-35","48-51","53-57"}.

Any guidance on how to achieve this would be appreciated!

Answer 1

Hi @Mansour_Dalir ,

To get the position of a substring in the original string, you can use the String.IndexOf method.

    Function MultiFinderString(BodyText As String, MultiFind As List(Of String)) As String()
        Dim result = New List(Of String) From {BodyText}
        Dim p As Integer = 0  ' Start position for searching

        For i = 0 To MultiFind.Count - 1
            Dim item = MultiFind(i)
            result = result.
                
                Where(Function(part) i = MultiFind.Count - 1 OrElse part.Contains(MultiFind(i + 1))).
                ToList()
        Next

        Dim positions = result.
            Select(Function(part)
                       Dim startIndex = BodyText.IndexOf(part, p)
                       Dim endIndex = startIndex + part.Length - 1
                       p = endIndex + 1  ' Move start position to after the found part
                       Return $"{startIndex}-{endIndex}"
                   End Function).
            ToArray()

        Return positions
    End Function

Best Regards.

Jiachen Li

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