String Math (Add and Subtract)
#1
Code: (Select All)
Screen _NewImage(1280, 720, 32)

a$ = "-10000000000000000000123.256"
b$ = " 60000000000000000000000.111"
Test a$, b$
a$ = " 100000000000000000000000000"
b$ = "-000000000000000000000000001.1"
Test a$, b$
a$ = "24123538548354853499345235498325489235982355952936529659265982635982398569.56466456"
b$ = "3.1"
Test a$, b$





Sub Test (a$, b$)
    Print "==========================================================================="
    Print a$
    Print b$
    Print "STEVE+:"; StringAdd(a$, b$)
    Print "BTEN +:"; BTen$(a$, "+", b$)
    Print "STEVE-:"; StringSubtract(a$, b$)
    Print "BTEN -:"; BTen$(a$, "-", b$)
    Print "==========================================================================="
    Sleep
End Sub


Function StringAdd$ (tempa$, tempb$)
    a$ = tempa$: b$ = tempb$ 'don't alter our original numbers
    Dim As _Unsigned _Integer64 a, b, c, carryover 'to hold our values

    'first fix the numbers to notmalize their lengths
    FixNumbers a$, b$
    'find the signs and strip them off
    If Left$(a$, 1) = "-" Then sa$ = "-": a$ = Mid$(a$, 2) Else sa$ = " "
    If Left$(b$, 1) = "-" Then sb$ = "-": b$ = Mid$(b$, 2) Else sb$ = " "
    'find the decimal position
    dp = InStr(a$, ".")
    If dp > 0 Then 'remove the decimal place from our numbers.  We can put it back later, in its proper position
        righta$ = Mid$(a$, dp + 1)
        rightb$ = Mid$(b$, dp + 1)
        a$ = Left$(a$, dp - 1) + righta$
        b$ = Left$(b$, dp - 1) + rightb$
    End If
    'our strings are now nothing but numbers with no signs and no decimals to deal with.  Let's start adding!
    'are we adding or really subtracting?

    If sa$ <> sb$ Then 'we're subtracting the two values if the signs aren't the same.
        Select Case a$
            Case Is < b$: s$ = sb$: Swap a$, b$ 'our sign is going to be determiined by b$
            Case Is = b$ 'if the two values are the same and are subtracting, our result is zero!
                StringAdd$ = "0" 'How easy was that?
                Exit Function
            Case Else: s$ = sa$ 'our sign is determined by a$
        End Select
        Do
            lb = Len(b$)
            a = Val(Right$(a$, 18)): a$ = Left$(a$, Len(a$) - 18)
            b = Val(Right$(b$, 18)): b$ = Left$(b$, Len(b$) - 18)
            If borrow Then b = b + 1~&& 'in case we had to borrow a digit for the last subtraction
            If a < b Then
                If lb < 18 Then a = a + 10 ^ lb Else a = a + 10 ^ 18
                borrow = -1
            Else
                borrow = 0
            End If
            c = a - b
            temp$ = _Trim$(Str$(c))
            answer$ = String$(18 - Len(temp$), "0") + temp$ + answer$
        Loop Until Len(a$) = 0
        'remove leading 0's
        Do Until Left$(answer$, 1) <> "0"
            answer$ = Mid$(answer$, 2)
        Loop
        'remember to add in the decimal place before finished
        dp = Len(righta$)
        If dp > 0 Then
            answer$ = Left$(answer$, Len(answer$) - dp) + "." + Right$(answer$, dp)
        End If
        StringAdd$ = s$ + answer$
        Exit Function
    End If

    Do
        a1$ = Right$(a$, 18)
        b1$ = Right$(b$, 18)
        a = Val(Right$(a$, 18)): a$ = Left$(a$, Len(a$) - 18)
        b = Val(Right$(b$, 18)): b$ = Left$(b$, Len(b$) - 18)
        c = a + b + carryover
        temp$ = _Trim$(Str$(c))
        If Len(temp$) > 18 Then 'see if we have an answer that is more than 18 digits
            temp$ = Right$(temp$, 18) 'keep 18 digits
            carryover = 1 'store one for carry over
        Else
            carryover = 0 'no carryover
        End If
        answer$ = String$(18 - Len(temp$), "0") + temp$ + answer$
    Loop Until Len(a$) = 0
    If carryover Then answer$ = "1" + answer$
    'remember to add in the decimal place before finished
    dp = Len(righta$)
    If dp > 0 Then
        answer$ = Left$(answer$, Len(answer$) - dp) + "." + Right$(answer$, dp)
    End If
    'remove leading 0's
    Do Until Left$(answer$, 1) <> "0"
        answer$ = Mid$(answer$, 2)
    Loop
    StringAdd$ = sa$ + answer$
End Function

Function StringSubtract$ (tempa$, tempb$)
    a$ = tempa$: b$ = tempb$
    FixNumbers a$, b$
    If Left$(b$, 1) = "-" Then b$ = Mid$(b$, 2) Else b$ = "-" + b$
    StringSubtract$ = StringAdd$(a$, b$)
End Function


Sub FixNumbers (a$, b$)
    'first remove scientific notation and spaces from both
    a$ = _Trim$(N2S$(a$)): b$ = _Trim$(N2S$(b$))
    'then find the decimal position for both and normalize the expressions
    d1 = InStr(a$, "."): d2 = InStr(b$, ".")
    If d1 <> 0 Then 'break down the left and right side of the decimal point for ease of processing  (this is a$)
        lefta$ = Left$(a$, d1 - 1)
        righta$ = Mid$(a$, d1)
    Else
        lefta$ = a$
    End If
    If d2 <> 0 Then 'break down the left and right side of the decimal point for ease of processing  (this is b$)
        leftb$ = Left$(b$, d2 - 1)
        rightb$ = Mid$(b$, d2)
    Else
        leftb$ = b$
    End If

    'normalize the right side of our expressions
    l1 = Len(righta$): l2 = Len(rightb$)
    If l1 < l2 Then
        addzero = l2 - l1
        If l1 = 0 Then righta$ = ".": addzero = addzero - 1
        righta$ = righta$ + String$(addzero, "0")
    ElseIf l1 > l2 Then
        addzero = l1 - l2
        'If l2 = 0 Then rightb$ = ".": addzero = addzero - 1
        rightb$ = rightb$ + String$(addzero, "0")
    End If



    'strip off any plus/minus signs from the two numbers.
    If Left$(lefta$, 1) = "-" Then signa$ = "-": lefta$ = Mid$(lefta$, 2)
    If Left$(leftb$, 1) = "-" Then signb$ = "-": leftb$ = Mid$(leftb$, 2)
    If Left$(lefta$, 1) = "+" Then signa$ = "": lefta$ = Mid$(lefta$, 2)
    If Left$(leftb$, 1) = "+" Then signb$ = "": leftb$ = Mid$(leftb$, 2)
    'normalize the left side of our expressions
    l1 = Len(lefta$): l2 = Len(leftb$)
    If l1 < l2 Then
        addzero = l2 - l1
        lefta$ = String$(addzero, "0") + lefta$
    ElseIf l1 > l2 Then
        addzero = l1 - l2
        leftb$ = String$(addzero, "0") + leftb$
    End If
    'and then put it all together
    a$ = signa$ + lefta$ + righta$
    b$ = signb$ + leftb$ + rightb$
End Sub





Function N2S$ (exp$) 'scientific Notation to String

    t$ = LTrim$(RTrim$(exp$))
    If Left$(t$, 1) = "-" Or Left$(t$, 1) = "N" Then sign$ = "-": t$ = Mid$(t$, 2)

    dp = InStr(t$, "D+"): dm = InStr(t$, "D-")
    ep = InStr(t$, "E+"): em = InStr(t$, "E-")
    check1 = Sgn(dp) + Sgn(dm) + Sgn(ep) + Sgn(em)
    If check1 < 1 Or check1 > 1 Then N2S = exp$: Exit Function 'If no scientic notation is found, or if we find more than 1 type, it's not SN!

    Select Case l 'l now tells us where the SN starts at.
        Case Is < dp: l = dp
        Case Is < dm: l = dm
        Case Is < ep: l = ep
        Case Is < em: l = em
    End Select

    l$ = Left$(t$, l - 1) 'The left of the SN
    r$ = Mid$(t$, l + 1): r&& = Val(r$) 'The right of the SN, turned into a workable long


    If InStr(l$, ".") Then 'Location of the decimal, if any
        If r&& > 0 Then
            r&& = r&& - Len(l$) + 2
        Else
            r&& = r&& + 1
        End If
        l$ = Left$(l$, 1) + Mid$(l$, 3)
    End If

    Select Case r&&
        Case 0 'what the heck? We solved it already?
            'l$ = l$
        Case Is < 0
            For i = 1 To -r&&
                l$ = "0" + l$
            Next
            l$ = "0." + l$
        Case Else
            For i = 1 To r&&
                l$ = l$ + "0"
            Next
    End Select

    N2S$ = sign$ + l$
End Function


Function DWD$ (exp$) 'Deal With Duplicates
    'To deal with duplicate operators in our code.
    'Such as --  becomes a +
    '++ becomes a +
    '+- becomes a -
    '-+ becomes a -
    t$ = exp$
    Do
        bad = 0
        Do
            l = InStr(t$, "++")
            If l Then t$ = Left$(t$, l - 1) + "+" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "+-")
            If l Then t$ = Left$(t$, l - 1) + "-" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "-+")
            If l Then t$ = Left$(t$, l - 1) + "-" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "--")
            If l Then t$ = Left$(t$, l - 1) + "+" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
    Loop Until Not bad
    DWD$ = t$
End Function




Function BTen$ (InTop As String, Op As String, InBot As String)
    Rem $DYNAMIC

    InTop = LTrim$(RTrim$(InTop))
    InBot = LTrim$(RTrim$(InBot))

    l = InStr(InTop, "-")
    If l = 0 Then l = InStr(InTop, "+")
    If l = 0 Then InTop = "+" + InTop
    l = InStr(InBot, "-")
    If l = 0 Then l = InStr(InBot, "+")
    If l = 0 Then InBot = "+" + InBot

    l = InStr(InTop, ".")
    If l = 0 Then InTop = InTop + "."
    l = InStr(InBot, ".")
    If l = 0 Then InBot = InBot + "."

    If Op$ = "-" Then
        Op$ = "+"
        If Mid$(InBot, 1, 1) = "-" Then Mid$(InBot, 1, 1) = "+" Else Mid$(InBot, 1, 1) = "-"
    End If


    TDP& = Check&(10, InTop$)
    BDP& = Check&(10, InBot$)

    If TDP& < 0 Or BDP& < 0 Then Exit Function

    TSign% = Check&(11, InTop$)
    BSign% = Check&(11, InBot$)

    ' Calculate Array Size

    If Op$ = Chr$(43) Or Op$ = Chr$(45) Then
        '    "+" (Add)  OR    "-" (Subtract)
        Temp& = 9
    ElseIf Op$ = Chr$(42) Or Op$ = Chr$(50) Then
        '      "*" (Multiply) OR "2" (SQRT Multiply)
        Temp& = 7
    Else
        Exit Function
    End If

    ' LSA (Left Side of Array)
    LSA& = TDP& - 2
    TLS& = LSA& \ Temp&
    If LSA& Mod Temp& > 0 Then
        TLS& = TLS& + 1
        Do While (TLPad& + LSA&) Mod Temp& > 0
            TLPad& = TLPad& + 1
        Loop
    End If
    LSA& = BDP& - 2
    BLS& = LSA& \ Temp&
    If LSA& Mod Temp& > 0 Then
        BLS& = BLS& + 1
        Do While (BLPad& + LSA&) Mod Temp& > 0
            BLPad& = BLPad& + 1
        Loop
    End If
    If TLS& >= BLS& Then LSA& = TLS& Else LSA& = BLS&

    ' RSA (Right Side of Array)
    RSA& = Len(InTop$) - TDP&
    TRS& = RSA& \ Temp&
    If RSA& Mod Temp& > 0 Then
        TRS& = TRS& + 1
        Do While (TRPad& + RSA&) Mod Temp& > 0
            TRPad& = TRPad& + 1
        Loop
    End If
    RSA& = Len(InBot$) - BDP&
    BRS& = RSA& \ Temp&
    If RSA& Mod Temp& > 0 Then
        BRS& = BRS& + 1
        Do While (BRPad& + RSA&) Mod Temp& > 0
            BRPad& = BRPad& + 1
        Loop
    End If
    If TRS& >= BRS& Then RSA& = TRS& Else RSA& = BRS&



    If Op$ = Chr$(43) Or Op$ = Chr$(45) Then
        '    "+" (Add)  OR    "-" (Subtract)

        Dim Result(1 To (LSA& + RSA&)) As Long

        If (Op$ = Chr$(43) And TSign% = BSign%) Or (Op$ = Chr$(45) And TSign% <> BSign%) Then
            ' Add Absolute Values and Return Top Sign

            ' Left Side
            For I& = 1 To LSA&
                ' Top
                If I& <= (LSA& - TLS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (1 + LSA& - TLS&) Then
                    Result(I&) = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                    TDP& = 11 - TLPad&
                Else
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                End If
                ' Bottom
                If I& <= (LSA& - BLS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (1 + LSA& - BLS&) Then
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, 2, (9 - BLPad&)))
                    BDP& = 11 - BLPad&
                Else
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                End If
            Next I&

            ' Right Side
            TDP& = TDP& + 1: BDP& = BDP& + 1
            For I& = (LSA& + 1) To (LSA& + RSA&)
                ' Top
                If I& > (LSA& + TRS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (LSA& + TRS&) Then
                    Result(I&) = (10 ^ TRPad&) * Val(Right$(InTop$, (9 - TRPad&)))
                Else
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                End If
                ' Bottom
                If I& > (LSA& + BRS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (LSA& + BRS&) Then
                    Result(I&) = Result(I&) + (10 ^ BRPad&) * Val(Right$(InBot$, (9 - BRPad&)))
                Else
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                End If
            Next I&

            ' Carry
            For I& = (LSA& + RSA&) To 2 Step -1
                If Result(I&) >= 1000000000 Then
                    Result(I& - 1) = Result(I& - 1) + 1
                    Result(I&) = Result(I&) - 1000000000
                End If
            Next I&

            ' Return Sign
            If TSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

        Else
            ' Compare Absolute Values

            If TDP& > BDP& Then
                Compare& = 1
            ElseIf TDP& < BDP& Then
                Compare& = -1
            Else
                If Len(InTop$) > Len(InBot$) Then Compare& = Len(InBot$) Else Compare& = Len(InTop$)
                For I& = 2 To Compare&
                    If Val(Mid$(InTop$, I&, 1)) > Val(Mid$(InBot$, I&, 1)) Then
                        Compare& = 1
                        Exit For
                    ElseIf Val(Mid$(InTop$, I&, 1)) < Val(Mid$(InBot$, I&, 1)) Then
                        Compare& = -1
                        Exit For
                    End If
                Next I&
                If Compare& > 1 Then
                    If Len(InTop$) > Len(InBot$) Then
                        Compare& = 1
                    ElseIf Len(InTop$) < Len(InBot$) Then
                        Compare& = -1
                    Else
                        Compare& = 0
                    End If
                End If
            End If

            ' Conditional Subtraction

            If Compare& = 1 Then
                ' Subtract Bottom from Top and Return Top Sign

                ' Top
                Result(1) = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                TDP& = 11 - TLPad&
                For I& = 2 To LSA&
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                Next I&
                TDP& = TDP& + 1
                For I& = (LSA& + 1) To (LSA& + TRS& - 1)
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                Next I&
                Result(LSA& + TRS&) = 10& ^ TRPad& * Val(Right$(InTop$, (9 - TRPad&)))

                ' Bottom
                BDP& = (Len(InBot$) - 17) + BRPad&
                For I& = (LSA& + BRS&) To (1 + LSA& - BLS&) Step -1
                    If I& = LSA& Then BDP& = BDP& - 1
                    If I& = (LSA& + BRS&) Then
                        Temp& = (10& ^ BRPad&) * Val(Right$(InBot$, (9 - BRPad&)))
                    ElseIf I& = (1 + LSA& - BLS&) Then
                        Temp& = Val(Mid$(InBot$, 2, (9 - BLPad&)))
                    Else
                        Temp& = Val(Mid$(InBot$, BDP&, 9))
                        BDP& = BDP& - 9
                    End If
                    If Result(I&) < Temp& Then
                        ' Borrow
                        For J& = (I& - 1) To 1 Step -1
                            If Result(J&) = 0 Then
                                Result(J&) = 999999999
                            Else
                                Result(J&) = Result(J&) - 1
                                Exit For
                            End If
                        Next J&
                        Result(I&) = Result(I&) + 1000000000
                    End If
                    Result(I&) = Result(I&) - Temp&
                Next I&

                ' Return Sign
                If TSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

            ElseIf Compare& = -1 Then
                ' Subtract Top from Bottom and Return Bottom Sign

                ' Bottom
                Result(1) = Val(Mid$(InBot$, 2, (9 - BLPad&)))
                BDP& = 11 - BLPad&
                For I& = 2 To LSA&
                    Result(I&) = Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                Next I&
                BDP& = BDP& + 1
                For I& = (LSA& + 1) To (LSA& + BRS& - 1)
                    Result(I&) = Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                Next I&
                Result(LSA& + BRS&) = 10& ^ BRPad& * Val(Right$(InBot$, (9 - BRPad&)))

                ' Top
                TDP& = (Len(InTop$) - 17) + TRPad&
                For I& = (LSA& + TRS&) To (1 + LSA& - TLS&) Step -1
                    If I& = LSA& Then TDP& = TDP& - 1
                    If I& = (LSA& + TRS&) Then
                        Temp& = (10& ^ TRPad&) * Val(Right$(InTop$, (9 - TRPad&)))
                    ElseIf I& = (1 + LSA& - TLS&) Then
                        Temp& = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                    Else
                        Temp& = Val(Mid$(InTop$, TDP&, 9))
                        TDP& = TDP& - 9
                    End If
                    If Result(I&) < Temp& Then
                        ' Borrow
                        For J& = (I& - 1) To 1 Step -1
                            If Result(J&) = 0 Then
                                Result(J&) = 999999999
                            Else
                                Result(J&) = Result(J&) - 1
                                Exit For
                            End If
                        Next J&
                        Result(I&) = Result(I&) + 1000000000
                    End If
                    Result(I&) = Result(I&) - Temp&
                Next I&

                ' Build Return Sign
                If BSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

            Else
                ' Result will always be 0

                LSA& = 1: RSA& = 1
                RetStr$ = Chr$(43)

            End If
        End If

        ' Generate Return String
        RetStr$ = RetStr$ + LTrim$(Str$(Result(1)))
        For I& = 2 To LSA&
            RetStr$ = RetStr$ + Right$(String$(8, 48) + LTrim$(Str$(Result(I&))), 9)
        Next I&
        RetStr$ = RetStr$ + Chr$(46)
        For I& = (LSA& + 1) To (LSA& + RSA&)
            RetStr$ = RetStr$ + Right$(String$(8, 48) + LTrim$(Str$(Result(I&))), 9)
        Next I&

        Erase Result

    ElseIf Op$ = Chr$(42) Then
        ' * (Multiply)

        Dim TArray(1 To (LSA& + RSA&)) As Long
        Dim BArray(1 To (LSA& + RSA&)) As Long
        Dim ResDBL(0 To (LSA& + RSA&)) As Double

        ' Push String Data Into Array
        For I& = 1 To LSA&
            If I& <= (LSA& - TLS&) Then
                ''' TArray(I&) = TArray(I&) + 0
            ElseIf I& = (1 + LSA& - TLS&) Then
                TArray(I&) = Val(Mid$(InTop$, 2, (7 - TLPad&)))
                TDP& = 9 - TLPad&
            Else
                TArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
            If I& <= (LSA& - BLS&) Then
                ''' BArray(I&) = BArray(I&) + 0
            ElseIf I& = (1 + LSA& - BLS&) Then
                BArray(I&) = Val(Mid$(InBot$, 2, (7 - BLPad&)))
                BDP& = 9 - BLPad&
            Else
                BArray(I&) = Val(Mid$(InBot$, BDP&, 7))
                BDP& = BDP& + 7
            End If
        Next I&
        TDP& = TDP& + 1: BDP& = BDP& + 1
        For I& = (LSA& + 1) To (LSA& + RSA&)
            If I& > (LSA& + TRS&) Then
                ''' TArray(I&) = TArray(I&) + 0
            ElseIf I& = (LSA& + TRS&) Then
                TArray(I&) = 10 ^ TRPad& * Val(Right$(InTop$, (7 - TRPad&)))
            Else
                TArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
            If I& > (LSA& + BRS&) Then
                ''' BArray(I&) = BArray(I&) + 0
            ElseIf I& = (LSA& + BRS&) Then
                BArray(I&) = 10 ^ BRPad& * Val(Right$(InBot$, (7 - BRPad&)))
            Else
                BArray(I&) = Val(Mid$(InBot$, BDP&, 7))
                BDP& = BDP& + 7
            End If
        Next I&

        ' Multiply from Arrays to Array
        For I& = (LSA& + TRS&) To (1 + LSA& - TLS&) Step -1
            For J& = (LSA& + BRS&) To (1 + LSA& - BLS&) Step -1
                Temp# = 1# * TArray(I&) * BArray(J&)
                If (I& + J&) Mod 2 = 0 Then
                    TL& = Int(Temp# / 10000000)
                    TR& = Temp# - 10000000# * TL&
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + 10000000# * TR&
                Else
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + Temp#
                End If
                If ResDBL((I& + J&) \ 2) >= 100000000000000# Then
                    Temp# = ResDBL((I& + J&) \ 2)
                    TL& = Int(Temp# / 100000000000000#)
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = Temp# - 100000000000000# * TL&
                End If
            Next J&
        Next I&

        Erase TArray, BArray

        ' Generate Return String
        If (TSign% * BSign%) = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)
        RetStr$ = RetStr$ + LTrim$(Str$(ResDBL(0)))
        For I& = 1 To (LSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 7) + Chr$(46) + Right$(RetStr$, 7)
        For I& = (LSA& + 1) To (LSA& + RSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&

        Erase ResDBL

    ElseIf Op$ = Chr$(50) Then
        ' 2 (SQRT Multiply)

        Dim IArray(1 To (LSA& + RSA&)) As Long
        Dim ResDBL(0 To (LSA& + RSA&)) As Double

        ' Push String Data Into Array
        For I& = 1 To LSA&
            If I& <= (LSA& - TLS&) Then
                ''' IArray(I&) = IArray(I&) + 0
            ElseIf I& = (1 + LSA& - TLS&) Then
                IArray(I&) = Val(Mid$(InTop$, 2, (7 - TLPad&)))
                TDP& = 9 - TLPad&
            Else
                IArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
        Next I&
        TDP& = TDP& + 1
        For I& = (LSA& + 1) To (LSA& + RSA&)
            If I& > (LSA& + TRS&) Then
                ''' IArray(I&) = IArray(I&) + 0
            ElseIf I& = (LSA& + TRS&) Then
                IArray(I&) = 10 ^ TRPad& * Val(Right$(InTop$, (7 - TRPad&)))
            Else
                IArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
        Next I&

        ' SQRT Multiply from Array to Array
        For I& = (LSA& + TRS&) To 1 Step -1
            For J& = I& To 1 Step -1
                Temp# = 1# * IArray(I&) * IArray(J&)
                If I& <> J& Then Temp# = Temp# * 2
                If (I& + J&) Mod 2 = 0 Then
                    TL& = Int(Temp# / 10000000)
                    TR& = Temp# - 10000000# * TL&
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + 10000000# * TR&
                Else
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + Temp#
                End If
                If ResDBL((I& + J&) \ 2) >= 100000000000000# Then
                    Temp# = ResDBL((I& + J&) \ 2)
                    TL& = Int(Temp# / 100000000000000#)
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = Temp# - 100000000000000# * TL&
                End If
            Next J&
        Next I&

        Erase IArray

        ' Generate Return String
        If (TSign% * BSign%) = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)
        RetStr$ = RetStr$ + LTrim$(Str$(ResDBL(0)))
        For I& = 1 To (LSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 7) + Chr$(46) + Right$(RetStr$, 7)
        ' Don't usually want the full right side for this, just enough to check the
        ' actual result against the expected result, which is probably an integer.
        ' Uncomment the three lines below when trying to find an oddball square root.
        'FOR I& = (LSA& + 1) TO (LSA& + RSA&)
        '    RetStr$ = RetStr$ + RIGHT$(STRING$(13, 48) + LTRIM$(STR$(ResDBL(I&))), 14)
        'NEXT I&

        Erase ResDBL

    End If

    ' Trim Leading and Trailing Zeroes
    Do While Mid$(RetStr$, 2, 1) = Chr$(48) And Mid$(RetStr$, 3, 1) <> Chr$(46)
        RetStr$ = Left$(RetStr$, 1) + Right$(RetStr$, Len(RetStr$) - 2)
    Loop
    Do While Right$(RetStr$, 1) = Chr$(48) And Right$(RetStr$, 2) <> Chr$(46) + Chr$(48)
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)
    Loop


    If Mid$(RetStr$, 1, 1) = "+" Then Mid$(RetStr$, 1, 1) = " "
    Do
        r$ = Right$(RetStr$, 1)
        If r$ = "0" Then RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)
    Loop Until r$ <> "0"

    r$ = Right$(RetStr$, 1)
    If r$ = "." Then RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)

    BTen$ = RetStr$
End Function
Rem $STATIC
' ---------------------------------------------------------------------------
' FUNCTION Check& (Op&, InString$)                Multi-Purpose String Tester
' ---------------------------------------------------------------------------
'
' *  Op&  = Type of string to expect and/or operation to perform
'
'  { 00A } = (10) Test Base-10-Format String  ( *!* ALTERS InString$ *!* )
'  { 00B } = (11) Read Sign ("+", "-", or CHR$(241))
'
'  Unlisted values are not used and will return [ Check& = 0 - Op& ].
'  Different Op& values produce various return values.
'  Refer to the in-code comments for details.
'
' ---------------------------------------------------------------------------
' FUNCTION Check& (Op&, InString$)                Multi-Purpose String Tester
' ---------------------------------------------------------------------------
Function Check& (Op As Long, InString As String)
    Rem $DYNAMIC

    RetVal& = Len(InString$)

    Select Case Op&

        Case 10
            ' {00A} Test String for Base-10-Format ( *!* ALTERS InString$ *!* )
            ' Returns:
            ' {& > 0} = DP offset; {& < 0} = FAILED at negative offset
            '
            ' After testing passes, the string is trimmed
            ' of nonessential leading and trailing zeroes.

            If RetVal& = 0 Then
                RetVal& = -1
            Else
                Select Case Asc(Left$(InString$, 1))
                    Case 43, 45 ' "+", "-"
                        For I& = 2 To RetVal&
                            Select Case Asc(Mid$(InString$, I&, 1))
                                Case 46 ' "."
                                    If DPC% > 0 Then
                                        RetVal& = 0 - I&
                                        Exit For
                                    Else
                                        DPC% = DPC% + 1
                                        RetVal& = I&
                                    End If
                                Case 48 To 57
                                    ' keep going
                                Case Else
                                    RetVal& = 0 - I&
                                    Exit For
                            End Select
                        Next I&
                    Case Else
                        RetVal& = -1
                End Select
                If DPC% = 0 And RetVal& > 0 Then
                    RetVal& = 0 - RetVal&
                ElseIf RetVal& = 2 Then
                    InString$ = Left$(InString$, 1) + Chr$(48) + Right$(InString$, Len(InString$) - 1)
                    RetVal& = RetVal& + 1
                End If
                If RetVal& = Len(InString$) Then InString$ = InString$ + Chr$(48)
                Do While Asc(Right$(InString$, 1)) = 48 And RetVal& < (Len(InString$) - 1)
                    InString$ = Left$(InString$, Len(InString$) - 1)
                Loop
                Do While Asc(Mid$(InString$, 2, 1)) = 48 And RetVal& > 3
                    InString$ = Left$(InString$, 1) + Right$(InString$, Len(InString$) - 2)
                    RetVal& = RetVal& - 1
                Loop
            End If


        Case 11
            ' {00B} Read Sign ("+", "-", or CHR$(241))
            ' Returns:
            ' Explicit: +1 = Positive; -1 = Negative; 0 = Unsigned;
            ' Implied: +64 = Positive; -64 = NULL String

            If RetVal& = 0 Then RetVal& = -64
            For I& = 1 To RetVal&
                Select Case Asc(Mid$(InString$, I&, 1))
                    Case 32
                        RetVal& = 64
                        ' keep going
                    Case 43
                        RetVal& = 1
                        Exit For
                    Case 45
                        RetVal& = -1
                        Exit For
                    Case 241
                        RetVal& = 0
                        Exit For
                    Case Else
                        RetVal& = 64
                        Exit For
                End Select
            Next I&


        Case Else

            RetVal& = 0 - Op&

    End Select

    Check& = RetVal&
End Function

Code to plug in and use for string math.  So far, I've only coded these for addition or subtraction, though the older BTEN$ also handles multiplication and SQRT.  I figured I'd toss these up here as it seems nearly every programmer ends up writing a sting math routine at some point in their coding career, and these should be easy enough to plug into any other program and use as a comparison test to make certain that results match.

Of course, if results don't match, and the issue is somehow with my code here, feel free to mention it to me and I'll try and dig into the problem and sort it out.  There's a lot of little tweaks which can toss string math off, so I wouldn't swear everything here is 100% bug-free, but it's got 2 different routines to compare against, if you need it.  AFAIK, things work without issues, but I wouldn't swear to anything.  After all, @Pete found a glitch earlier where my integer64 variables were trying to do floating point math, and I *never* would've expected that ! (Especially just to add 1 for carryover!!)

I reserve the right to always hide glitches somewhere in the code for... umm.... for...  for learning experience!  Yeah!  There might be some in there for the learning experience!  Big Grin
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