Get Unique Values from a Comma-Delimited String

Level: Intermediate

Knowledge Required:

• Array
• String

Description:
Here is a function that extracts out the unique values from comma delimited string.

Public Function GetUnique( _
                ByVal sStringToUse As String, _
                Optional ByVal sSeperator As String = ",", _
                Optional ByVal LimitWords As Integer = 0 _
                ) As String
    Dim sStrings() As String
    Dim sToRet As String = ""

    sStrings = sStringToUse.Split(sSeperator)

    Dim i As Integer = 0
    For Each s As String In sStrings            ' for each item in array
        Dim sTrimed As String = s.Trim()
        ' if limit is supplied and also limit is NOT over
        If Not (LimitWords < 1 OrElse i < LimitWords) Then Exit For
        ' if this item is NOT added previously
        If sToRet.IndexOf(sTrimed, StringComparison.CurrentCultureIgnoreCase) < 0 Then
            i += 1
            sToRet &= sTrimed & ","             ' add it in list
        End If
    Next

    If sToRet.Length > 0 Then                 ' if items found
        ' return them
        Return sToRet.ToString().Substring(0, sToRet.Length - 1)
    Else    ' else (item NOT found)
        Return ""    ' return empty string
    End If
End Function

Usage:

Dim a As String
a = "computer,hardware,computer,software,hardware,tools,downloads,software"
Debug.Print(GetUnique(a))

Output:
computer,downloads,hardware,software,tools