小吳 VBQA 程式設計討論

請問各位高手..
我要寫一個程式 將阿拉伯數字轉換成羅馬數字
範圍只要從1~3999 當我輸入負數的時候為何會出現over flow的訊息
另外..還有當我輸入4000的時候 會顯示四個M
輸出結果 同一個符號不能連續出現四次
例如: 4 不等於IIII (要變成 IV)
9=IX
　　　14=XIV
　　　40=XL
...............以此類推
但是...我假設我不知道5000的符號
所以不能算出4000以上的數字
請問我要怎麼樣才能把範圍設在1~3999呢?
謝謝各位的幫忙!!
I=1
V=5
X=10
L=50
C=100
D=500
M=1000
以下是程式碼部分:

Function ToRoman(x As Integer) As String
'function provided by Jason Roozee
　　 'jason@vbhelp.com
　　 'www.VBHelp.com
Dim sFinished As String
sFinished = String(Int(x / 1000), "M")
x = x - (Int(x / 1000) * 1000)
If x ＞= 900 Then
sFinished = sFinished & "CM"
ElseIf x ＞= 500 And x ＜ 900 Then
sFinished = sFinished & "D" & String(Int((x - 500) / 100), "C")
ElseIf x ＞= 400 And x ＜ 500 Then
sFinished = sFinished & "CD"
Else
sFinished = sFinished & String(Int(x / 100), "C")
End If
x = x - (Int(x / 100) * 100)

If x ＞= 90 Then
sFinished = sFinished & "XC"
ElseIf x ＞= 50 And x ＜ 90 Then
sFinished = sFinished & "L" & String(Int((x - 50) / 10), "X")
ElseIf x ＞= 40 And x ＜ 50 Then
sFinished = sFinished & "XL"
Else
sFinished = sFinished & String(Int(x / 10), "X")
End If
x = x - (Int(x / 10) * 10)

If x ＞= 9 Then
sFinished = sFinished & "IX"
ElseIf x ＞= 5 And x ＜ 9 Then
sFinished = sFinished & "V" & String(Int((x - 5) / 1), "I")
ElseIf x ＞= 4 And x ＜ 5 Then
sFinished = sFinished & "IV"
Else
sFinished = sFinished & String(Int((x / 1) / 1), "I")
End If
ToRoman = sFinished
　　



End Function
Private Sub cmdRoman_Click()
Dim intHindu As Integer
Dim strRoman As String

　　strRoman = ToRoman(txtHindu)
　　
　　lblRoman.Caption = "The Roman Number is " & """" & strRoman & """"
　　　　
End Sub