randomstring.txt

一部分关于VB编程的小技巧

'**************************************
' Name: Generate a random string, with a
'     length within a range.
' Description:This code will take a rang
'     e (lower and upper), and output a string
'     of random characters (0-9, A-Z, a-z). I 
'     use this to generate a key for encryptio
'     n, during the key negotiation phase of a
'     connection to an encrypted server.
Usage is simple:
Dim sKey as String
sKey = GenerateKey(10,100)
' this code generates a key with a lengt
'     h between
' 10 and 100 characters.
' By: Gregg Housh
'
' Inputs:iLower: Lowest possible length 


'     for the string
    iUpper: Maximum length For the String
'
' Returns:Returns a string.
'
'This code is copyrighted and has' limited warranties.Please see http://w
'     ww.Planet-Source-Code.com/xq/ASP/txtCode
'     Id.21395/lngWId.1/qx/vb/scripts/ShowCode
'     .htm'for details.'**************************************

' Credit goes to these people for code I
'     
' borrowed/modified:
' Kevin Lawrence - non-repeating random 
'     
' number generator
' VBPJ - GenerateRandomNumberInRange 
' (modified by me, from a shuffle routin
'     e in VBPJ)


Public Function GenerateKey(ByVal iLower As Integer, ByVal iUpper As Integer) As String
    Dim sKey As String
    Dim sChar As String
    Dim iLen As Integer
    Dim iLoop As Integer
    ' dont need keys TOO big ...
    iLen = GetRandomNumberInRange(iLower, iUpper)


    For iLoop = 1 To iLen
        ' dont include quotes
        Retry:


        Do
            sChar = Chr(GetRandomNumber())
        Loop While sChar = Chr(34)
        ' make sure its 0-9, A-Z, or a-z


        If Not IsValidChar(sChar) Then
            Goto Retry:
        Else
            sKey = sKey & sChar
        End If
    Next iLoop
    GenerateKey = sKey
End Function


Private Function IsValidChar(ByVal sChar As String) As Boolean
    Dim btoggle As Boolean


    If Asc(sChar) >= 48 And Asc(sChar) <= 57 Then
        'valid #
        btoggle = True
    ElseIf Asc(sChar) >= 65 And Asc(sChar) <= 90 Then
        'valid uppercase character
        btoggle = True
    ElseIf Asc(sChar) >= 97 And Asc(sChar) <= 122 Then
        btoggle = True
    Else
        btoggle = False
    End If
    IsValidChar = btoggle
End Function


Public Function GetRandomNumberInRange(Lower As Integer, Upper As Integer) As Integer
    Static PrimeFactor(10) As Integer
    Static a As Integer
    Static c As Integer
    Static b As Integer
    Static s As Long
    Static n As Integer
    Static n1 As Integer
    Dim i As Integer
    Dim j As Integer
    Dim K As Integer
    Dim m As Integer
    Dim t As Boolean


    If (n <> Upper - Lower + 1) Then
        n = Upper - Lower + 1
        i = 0
        n1 = n
        K = 2


        Do While K <= n1


            If (n1 Mod K = 0) Then


                If (i = 0 Or PrimeFactor(i) <> K) Then
                    i = i + 1
                    PrimeFactor(i) = K
                End If
                n1 = n1 / K
            Else
                K = K + 1
            End If
        Loop
        b = 1


        For j = 1 To i
            b = b * PrimeFactor(j)
        Next j
        If n Mod 4 = 0 Then b = b * 2
        a = b + 1
        c = Int(n * 0.66)
        t = True


        Do While t
            t = False


            For j = 1 To i
                If ((c Mod PrimeFactor(j) = 0) Or (c Mod a = 0)) Then t = True
            Next j
            If t Then c = c - 1
        Loop
        Randomize
        s = Rnd(n)
    End If
    s = (a * s + c) Mod n
    GetRandomNumberInRange = s + Lower
End Function


Public Function GetRandomNumber() As Integer
    Dim a(122) ' Sets the maximum number To pick
    Dim b(122) ' Will be the list of new numbers (same as DIM above)
    Dim ChosenNumber As Integer
    Dim MaxNumber As Integer
    Dim seq As Integer
    'Set the original array
    MaxNumber = 122 ' Must equal the Dim above


    For seq = 0 To MaxNumber
        a(seq) = seq
    Next seq
    'Main Loop (mix em all up)
    Randomize (Timer)


    For seq = MaxNumber To 0 Step -1
        ChosenNumber = Int(seq * Rnd)
        b(MaxNumber - seq) = a(ChosenNumber)
        a(ChosenNumber) = a(seq)
    Next seq
    ' return a random number from a random p
    '     osition in B()
    GetRandomNumber = b(GetRandomNumberInRange(1, 122))
End Function