VBA Find Partial String in String Array and Output the Found String Array Value

Okay, so I am trying to do a sort of index match thing using VBA. What I am attempting to do is to use the prefix of a long number and try to find that exact prefix in a string array, and output that string array value. So this is what I have so far as a test:

Function abc(s As String) As String
Dim PRE(11) As String
Dim str As String


PRE(0) = "PREFIXAAA"
PRE(1) = "PREFIXB"
PRE(2) = "PREFIXCCCCC"
PRE(3) = "PREFIX1AAA"

....

str = Cells(1, 1).Text

    If IIA(str, PREFIX) = True Then
        MsgBox ("YES")
      
        Else
        MsgBox ("NO")
        End If

End Function



Function IIA(stringToBeFound As String, arr As Variant) As Boolean
    IIA = Not IsError(Application.Match(stringToBeFound, arr, 0))
End Function

So I can match the text exactly so if I put PREFIXB in cell A1 in this example, i will get the msg box saying "YES", but if I make it PREFIXB1231k4j3jj1kj32cj, it will display "NO". I want to get it so that PREFIXB will be displayed in the cell that I put the formula in. So if A1 = "PREFIX1AAA100CF" and cell B1 = "=ABC(A1)", cell B1 will display "PREFIX1AAA".

Now the thing is that these prefixes can have different lengths, but will never encompass the exact prefix of another. So if I had a prefix of: PRE1AB, I won't have a prefix of PRE1A.

Thanks for any help!

I am not really using s as an input parameter for this code. For some reason the code only works with (s as string) in there. I came up with my own solution to this problem (any input/advice would be appreciated); however, it isn't very elegant:

Function abc(S As String) As String
Dim PREFIX(11) As String
Dim LENGTH(11) As String
Dim min As Long
Dim max As Long
Dim Full As String
Dim Part As String
Dim Ans As String

'Define Array Values
PREFIX(0) = "PRE1"
PREFIX(1) = "PRE2"
PREFIX(2) = "PRE3A"
PREFIX(3) = "PRE44444"
PREFIX(4) = "PRE5"
PREFIX(5) = "PRECCCCCCCCC"
...

' Choose Cell Value to Compare to Array
Full = Cells(1, 1).Text

' Obtain Array Text Length (LBound, UBound)
For j = LBound(PREFIX) To UBound(PREFIX)
LENGTH(j) = Len(PREFIX(j))
Next j


' Find Min and Max Text Length
min = 100
max = -100

For k = LBound(PREFIX) To UBound(PREFIX)
    If LENGTH(k) > max Then max = LENGTH(k)
    If LENGTH(k) < min Then min = LENGTH(k)
Next

' Find Match in Array
For i = min To max

    Part = Left(Full, i)
    
    If IIA(Part, PREFIX) = True Then
        Ans = Application.WorksheetFunction.Index(PREFIX, Application.WorksheetFunction.Match(Part, PREFIX, 0))
        abc = Ans
    Else
    End If
Next i

    
End Function



Function IIA(stringToBeFound As String, arr As Variant) As Boolean
    IIA = Not IsError(Application.Match(stringToBeFound, arr, 0))
End Function