进制数换算

'十进制数转换成十六进制数
    Public Shared Function DecToHex(ByVal value As Integer) As String
        Return BinToHex(DecToBin(value))
    End Function

    '二进制数转换成十进制数
    Public Shared Function BinToDec(ByVal value As String) As Integer
        Dim i As Integer
        Dim returnValue As Integer = 0
        For i = value.Length - 1 To 0 Step -1
            returnValue += Val(value.Chars(value.Length - 1 - i)) * (2 ^ i)
        Next

        Return returnValue
    End Function

    '任意二进制数转换成十六进制数
    Public Shared Function BinToHex(ByVal value As String) As String
        If value.Length Mod 4 <> 0 Then
            value = value.PadLeft(4 * (value.Length / 4 + 1), "0"c)
        End If

        Dim i As Integer
        Dim returnString As String = ""
        Dim tempString As String
        For i = 0 To value.Length / 4 - 1
            tempString = value.Chars(4 * i) + value.Chars(4 * i + 1) _
                     + value.Chars(4 * i + 2) + value.Chars(4 * i + 3)

            returnString += GetHexChar(tempString)
        Next

        Return returnString
    End Function

    '特殊情况：4位二进制数转换成十六进制数
    Public Shared Function GetHexChar(ByVal value As String) As String
        Dim tempValue As Integer
        tempValue = BinToDec(value)

        If tempValue < 10 Then
            Return CStr(tempValue)
        Else
            Select Case tempValue - 10
                Case 0
                    Return "A"
                Case 1
                    Return "B"
                Case 2
                    Return "C"
                Case 3
                    Return "D"
                Case 4
                    Return "E"
                Case 5
                    Return "F"
            End Select
        End If
    End Function

    '仅限非负整数
    '十进制数转换成二进制数
    Public Shared Function DecToBin(ByVal value As Integer) As String
        If value = 0 Then Return "0"

        Dim tempValue As Integer = value
        Dim tempString As String = ""

        Dim modValue As Integer
        Do
            tempString += CStr(tempValue Mod 2)
            tempValue = tempValue / 2
        Loop While (tempValue <> 0)

        Dim i As Integer
        Dim returnChars As Char() = tempString.ToCharArray()
        Dim returnString As String = ""
        For i = tempString.Length - 1 To 0 Step -1
            returnString += returnChars(i)
        Next

        Return returnString
    End Function

    '十六进制数转换成十进制数
    Public Shared Function HexToDec(ByVal value As String) As Integer
        Dim i As Integer
        Dim returnValue As Integer = 0
        For i = value.Length - 1 To 0 Step -1
            Dim num As Integer = 0
            Select Case value.Chars(value.Length - 1 - i)
                Case "0"c To "9"c
                    num = Val(value.Chars(i))
                Case "A"c
                    num = 10
                Case "B"c
                    num = 11
                Case "C"c
                    num = 12
                Case "D"c
                    num = 13
                Case "E"c
                    num = 14
                Case "F"c
                    num = 15
            End Select

            returnValue += num * (16 ^ i)
        Next

        Return returnValue
    End Function