D&D Roll Die Excel Macro

Public Sub rolldie()

    On Error GoTo ErrHandler:

    Dim showDebug As Boolean
    showDebug = False

    Dim numRolls As Integer
    Dim currDieCnt As Integer
    Dim currDieRoll As Integer
    Dim numDie As Integer
    Dim dieSize As Integer
    Dim modifier As Integer
    Dim finalRoll As Integer
    Dim inputArray() As String
    Dim debugStr As String

    numRolls = WorksheetFunction.CountA(Selection)

    If numRolls = 0 Then Exit Sub

    For Each currRoll In Selection.Columns(1).Cells

        If InStr(1, LCase(currRoll.Value), "d") = 0 Then GoTo NextIteration

        currDieRoll = 0
        finalRoll = 0
        debugStr = ""

        inputArray = Split(LCase(Replace(currRoll.Value, " ", "")), "d", 2)

        numDie = CInt(inputArray(0))

        If InStr(inputArray(1), "+") > 0 Then
            inputArray = Split(inputArray(1), "+", 2)
            dieSize = CInt(inputArray(0))
            modifier = CInt(inputArray(1))
        Else
            dieSize = inputArray(1)
            modifier = 0
        End If

        For currDieCnt = 1 To numDie

            currDieRoll = CInt(Rnd() * dieSize + 1)
            finalRoll = finalRoll + currDieRoll

            If currDieCnt > 1 Then
                debugStr = debugStr & " + " & CStr(currDieRoll)
            Else
                debugStr = CStr(currDieRoll)
            End If

        Next

        If modifier > 0 Then
            finalRoll = finalRoll + modifier
            debugStr = debugStr & " + " & CStr(modifier)
        End If

        currRoll.Offset(0, 1).Value = CStr(finalRoll)

        If showDebug Then
            currRoll.Offset(0, 2).Value = debugStr
        End If

NextIteration:
    Next

    Exit Sub

ErrHandler:

    Set Selection.Offset(0, 1).Value = "Error"

End Sub