are you telling the computer to replace the value with one you have already calculated

you can teach the computer how to calculate each value without telling it to memorise every roman numeral... just like you know MCMXCII is 1992

whenever a smaller value is preceded by a larger CM or XC (100=C being less than 1000=M and 10=X less than 100=C) then you know to add the greater to the total sum and subtract the lesser... eg. add a thousand but subtract a hundred.

MCMXCII is really : M - C + M - X + C + I + I

no need to memorise the whole thing...

here a couple of functions that do this...

' at the top of your code you need this user defined type (udt)

Private Structure udtRomanNumeral

Dim value As Short

Dim symbol As String

End Structure

Public Function getRomanSymbolValue(ByVal strSymbol As String) As Int16

Static udrNumerals(6) As udtRomanNumeral

Static bolInit As Boolean

Dim intCounter As Integer

' this function gets a symbol I, V, X, L, C, D or M and returns their integer values 1, 5, 10, 50, 100, 500 or 1000 respectively

If Not bolInit Then

bolInit = True

udrNumerals(0).value = 1

udrNumerals(0).symbol = "I"

udrNumerals(1).value = 5

udrNumerals(1).symbol = "V"

udrNumerals(2).value = 10

udrNumerals(2).symbol = "X"

udrNumerals(3).value = 50

udrNumerals(3).symbol = "L"

udrNumerals(4).value = 100

udrNumerals(4).symbol = "C"

udrNumerals(5).value = 500

udrNumerals(5).symbol = "D"

udrNumerals(6).value = 1000

udrNumerals(6).symbol = "M"

End If

getRomanSymbolValue = -1

For intCounter = 0 To 6

If strSymbol = udrNumerals(intCounter).symbol Then

getRomanSymbolValue = udrNumerals(intCounter).value

Exit Function

End If

Next intCounter

End Function

Public Function evaluateRomanNumeral(ByVal strRoman As String) As Int16

' this function receives a string and evaluates it as a roman numeral and then returns its integer equivalent

' it does this by chopping off the leading characters. Since roman symbols decrease in value from left to right (except when subtracting 1x10^x, e.g. IV, IX, XL, XC, CD or CM)

' then add this value to total, unless it is followed by another symbol of greater value(see previous line)

Dim intTemp, intRank As Integer

Dim numRank As Short

Dim intCounter As Integer

Dim intLeadingCounter As Integer

Dim strSymbol, strThisSymbol As String

Dim strNextSymbol As String

Dim intValue, intThisValue As Integer

Dim intNextValue As Integer

Dim intRank1 As Integer

Dim intRank2 As Integer

Dim strPartialRomant As String

Dim bolLoop As Boolean

Dim strRanking As String

Dim strRememberInputParameter As String

On Error GoTo handler

strRememberInputParameter = strRoman

strRanking = "IVXLCDM" ' this is used to determine whether one symbol is ranked higher than another by testing the result of instr() for two adjacent symbols

For intCounter = 1 To Len(strRoman)

If InStr(strRanking, Mid(strRoman, intCounter, 1)) = 0 Then

evaluateRomanNumeral = 0 ' if a symbol appears in the input parameter 'strRoman' that does is not a valid Roman Numeral symbol then the output is zero and exit function

Exit Function

End If

Next intCounter

startEvaluateRomanNumeralLoop:

Do While Len(strRoman) > 0

strThisSymbol = Mid(strRoman, 1, 1)

If Len(strRoman) > 1 Then

If Mid(strRoman, 2, 1) <> strThisSymbol Then

' if the first symbol (we are chopping off from the left as we go) is lesser in rank than its following symbol then we need to subtract the first and add the second

intRank1 = InStr(strRanking, strThisSymbol)

intRank2 = InStr(strRanking, Mid(strRoman, 2, 1))

If intRank2 > intRank1 Then

' iv, ix, xl, xc, cd, or cm and such

evaluateRomanNumeral = evaluateRomanNumeral - getromanSymbolValue(strThisSymbol)

evaluateRomanNumeral = evaluateRomanNumeral + getromanSymbolValue(Mid(strRoman, 2, 1))

strRoman = Mid(strRoman, 3)

GoTo startEvaluateRomanNumeralLoop

End If

End If

End If

' since we did not GoTo startEvaluateRomanNumeralLoop we know that this first symbol is the highest in the remaining string and must be added

' count the number of times it appears, multiply that number by its value and add it to the total count

intLeadingCounter = 0 : bolLoop = True

Do

If Len(strRoman) > 0 Then

If Mid(strRoman, 1, 1) = strThisSymbol Then

intLeadingCounter = intLeadingCounter + 1

strRoman = Mid(strRoman, 2)

Else

bolLoop = False

End If

Else

bolLoop = False

End If

Loop While bolLoop

intValue = getRomanSymbolValue(strThisSymbol)

evaluateRomanNumeral = evaluateRomanNumeral + intLeadingCounter * intValue

Loop

' here we test our result with this function's complement, if all is well then we're happy

If Not UCase(getRomanNumeral(evaluateRomanNumeral)) = UCase(strRememberInputParameter) Then

evaluateRomanNumeral = 0

End If

Exit Function

handler:

Stop

Resume

End Function

Public Function getRomanNumeral(ByVal lngValue As Integer) As String

' this function receives an integer value and returns its Roman numeral equivalent in the form of a string

' it does this by subtracting the value of the highest ranking symbol as it keeps a tally of the count

Static udrNumerals(6) As udtRomanNumeral

Static bolInit As Boolean

Dim intValue As Short

Dim intTemp, intRank As Object

Dim numRank As Short

On Error GoTo handler

If Not bolInit Then

bolInit = True

udrNumerals(0).value = 1

udrNumerals(0).symbol = "I"

udrNumerals(1).value = 5

udrNumerals(1).symbol = "V"

udrNumerals(2).value = 10

udrNumerals(2).symbol = "X"

udrNumerals(3).value = 50

udrNumerals(3).symbol = "L"

udrNumerals(4).value = 100

udrNumerals(4).symbol = "C"

udrNumerals(5).value = 500

udrNumerals(5).symbol = "D"

udrNumerals(6).value = 1000

udrNumerals(6).symbol = "M"

End If

getRomanNumeral = ""

If lngValue > 3899 Then ' there is a limit to the input value... anything that requires a symbol for 5000 (D with a bar above) does not work... MMMDCCCXCIX ... 3899

Exit Function

End If

intValue = lngValue

Do While intValue > udrNumerals(6).value

intTemp = intValue Mod udrNumerals(6).value

numRank = intTemp / udrNumerals(6).value ' this is the number of 1000s

getRomanNumeral = getRomanNumeral & udrNumerals(6).symbol 'L

intValue = intValue - udrNumerals(6).value

Loop

' now the value is less than 1000

intRank = 5

Do While intValue > 0

If intRank Mod 2 = 1 Then

' this is either 5, 50 or 500

intTemp = intValue Mod udrNumerals(intRank).value

If intValue >= udrNumerals(intRank).value Then ' >= 5

If intValue >= udrNumerals(intRank + 1).value - udrNumerals(intRank - 1).value Then ' >= 9

getRomanNumeral = getRomanNumeral & udrNumerals(intRank - 1).symbol & udrNumerals(intRank + 1).symbol ' IX

intValue = intValue + udrNumerals(intRank - 1).value - udrNumerals(intRank + 1).value ' -1+10

ElseIf intValue >= udrNumerals(intRank).value + 3 * udrNumerals(intRank - 1).value Then ' >= 8

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank - 1).symbol & udrNumerals(intRank - 1).symbol & udrNumerals(intRank - 1).symbol ' VIII

intValue = intValue - udrNumerals(intRank).value - 3 * udrNumerals(intRank - 1).value ' + 5 + 3

ElseIf intValue >= udrNumerals(intRank).value + 2 * udrNumerals(intRank - 1).value Then ' >= 7

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank - 1).symbol & udrNumerals(intRank - 1).symbol ' VII

intValue = intValue - udrNumerals(intRank).value - 2 * udrNumerals(intRank - 1).value ' + 5 + 2

ElseIf intValue >= udrNumerals(intRank).value + udrNumerals(intRank - 1).value Then ' >= 6

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank - 1).symbol ' VI

intValue = intValue - udrNumerals(intRank).value - udrNumerals(intRank - 1).value ' + 5 + 1

Else ' >= 5

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol ' V

intValue = intValue - udrNumerals(intRank).value ' + 5

End If

Else

intRank = intRank - 1

End If

Else

' this is either 1, 10, 100

If intValue >= udrNumerals(intRank).value Then ' >= 1 but < 5

If intValue >= udrNumerals(intRank + 1).value - udrNumerals(intRank).value Then ' >= 4

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank + 1).symbol ' IV

intValue = intValue + udrNumerals(intRank).value - udrNumerals(intRank + 1).value

ElseIf intValue >= 3 * udrNumerals(intRank).value Then ' >= 3

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank).symbol & udrNumerals(intRank).symbol ' III

intValue = intValue - 3 * udrNumerals(intRank).value

ElseIf intValue >= 2 * udrNumerals(intRank).value Then ' >= 2

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol & udrNumerals(intRank).symbol ' II

intValue = intValue - 2 * udrNumerals(intRank).value

Else ' >= 1

getRomanNumeral = getRomanNumeral & udrNumerals(intRank).symbol ' III

intValue = intValue - udrNumerals(intRank).value

End If

Else

intRank = intRank - 1

End If

End If

Loop

Exit Function

handler:

Stop

Resume

End Function

Public Function isARomanNumeral(ByVal strWord As String) As Boolean

' this function tests if the input is a valid roman numeral

isARomanNumeral = False

If Len(strWord) > 0 Then

If UCase(Trim(getRomanNumeral(evaluateRomanNumeral(strWord)))) = UCase(Trim(strWord)) Then

isARomanNumeral = True

End If

End If

End Function