Dim Shared As String stack, queue, token
stack = ""
queue = ""
token = "#"

Function word_(s As String, n As Integer, sep As String = " ") As String
    Dim As Integer pio, cnt, posic, i

    pio = 1 : cnt = 0 : posic = 0
    For i = 1 To Len(s)
        If Mid(s, i, Len(sep)) = sep Then
            cnt += 1
            If cnt = n - 1 Then pio = i + Len(sep)
            If cnt = n Then posic = i: Exit For
        End If
    Next

    If cnt < n Then Return ""
    If posic = 0 Then posic = Len(s) + 1

    Return Mid(s, pio, posic - pio)
End Function

Sub stackPush(s As String)
    stack = s & "|" & stack
End Sub

Sub queuePush(s As String)
    queue = queue & s & "|"
End Sub

Function queuePop() As String
    Dim As String result = word_(queue, 1, "|")
    queue = Mid(queue, Instr(queue, "|") + 1)
    Return result
End Function

Function isOperator(op As String) As Boolean
    Return Instr("+-*/^", op) <> 0 And Len(op) = 1
End Function

Function precedence(op As String) As Integer
    If isOperator(op) Then
        Return 1 + (Instr("+-*/^", op) <> 0) + (Instr("*/^", op) <> 0) + (Instr("^", op) <> 0)
    End If
End Function

Function stackPop() As String
    Dim As String result = word_(stack, 1, "|")
    stack = Mid(stack, Instr(stack, "|") + 1)
    Return result
End Function

Function stackPeek() As String
    Return word_(stack, 1, "|")
End Function

Function reverse(s As String) As String
    Dim As String result = ""
    Dim As String token = "#"
    Dim As Integer i = 0

    While token <> ""
        i += 1
        token = word_(s, i, "|")
        result = token & " " & result
    Wend

    Return result
End Function

Dim As String test = "3 + 4 * 2 / ( 1 - 5 ) ^ 2 ^ 3"
Print !"Input:\n"; test; !"\nNo", "token", "stack", "queue"

Dim As Integer i = 0
Do
    i += 1
    token = word_(test, i)
    If token = "" Then Exit Do
    Print i, token, reverse(stack), queue

    Select Case token
    Case "("
        stackPush(token)

    Case ")"
        While stackPeek() <> "("
            If stack = "" Then Print "Error: no matching '(' for token "; i: Sleep: End
            queuePush(stackPop())
        Wend
        Dim As String discard = stackPop()   'discard "("

    Case Else
        If isOperator(token) Then
            Dim As String op1 = token
            While isOperator(stackPeek())
                Dim As String op2 = stackPeek()
                If op2 <> "^" And precedence(op1) = precedence(op2) Then
                    queuePush(stackPop())
                Else
                    Exit While
                End If
            Wend
            stackPush(op1)
        Else   'number
            queuePush(token)
        End If
    End Select
Loop

While stack <> ""
    If stackPeek() = "(" Then Print "no matching ')'": Sleep:End
    queuePush(stackPop())
Wend

Print !"\nOutput:"
While queue <> ""
    Print queuePop(); " ";
Wend

Sleep