נושא: בעיה התכנית - "מחולל" רצפים של כל המחרוזו

Module Module1

    'First of all I would like to say that the reason I use global

    'variables in all of my subs Is that I have been seeing some memory

    'problems.

    Dim abcStr As String = ""       'the string we change (generate)

    Dim lastabcStr As String = ""   'the last string we want to come to

    Const minChar As Char = "a"     'the smaller letter

    Const maxChar As Char = "c"     'the bigger letter

    Dim len As Integer = 10         'the max length of the string we want to generate

    Dim i As Integer                  'this is just a variable for loops

    Dim notFound As Boolean         'another varilable for while loops

    ''' <summary>

    ''' the sub putCharAtPos insert a char instead of an existing char

    ''' it was created since the chars property of the string is readonly

    ''' </summary>

    ''' <param name="s">the string variable</param>

    ''' <param name="pos">the position of the char</param>

    ''' <param name="c">the new char to insert</param>

    ''' <remarks></remarks>

    Sub putCharAtPos(ByRef s As String, ByVal pos As Integer, ByVal c As Char)

        s = Left(s, pos) + c.ToString + Right(s, s.Length - pos - 1)

    End Sub

    ''' <summary>

    ''' the sub is for generating the next combination of chars

    ''' and showing it...

    ''' </summary>

    ''' <remarks>recursive</remarks>

    Sub nextAbc()

        If abcStr.Length < len Then ' if the number of letters is not the last one

             notFound = True ' will tell us if we can steel go on with this number of letters

             i = 0           ' will point to to the char we want to check

             While (i < abcStr.Length) And (notFound) ' while we didn't find a letter that can't be Increased

                 If abcStr.Chars(i) = maxChar Then ' if this letter can't be Increased

                     i += 1  ' I will point to the next letter

                 Else ' if this letter can be Increased

                     notFound = False

                End If ' abcStr.Chars(i) = maxChar

             End While ' (i < abcStr.Length) And (notFound)

             If notFound Then ' if this hole string can't be Increased

                 WriteLine(abcStr) ' we show the string

                 Beep(3000, 750) ' show when adding a letter

                 i = abcStr.Length   '

                 abcStr = ""         ' we generate a string that will be lengthed one char more than the last one

                 For i = 0 To i      ' and all chars will the smaller char.

                     abcStr += minChar.ToString

                 Next ' for i =0 to i (the length of abcStr)

             End If ' notFound

        End If ' abcStr.Length < len

        If abcStr < Left(lastabcStr, abcStr.Length) Then ' if the string is not the last one

             WriteLine(abcStr)   ' show the string

             i = abcStr.Length - 1 ' points to the last letter

             notFound = True         ' the letter can be Increased

             While (i > 0) And (notFound)

                 If abcStr.Chars(i) >= maxChar Then

                     putCharAtPos(abcStr, i, minChar)

                     i -= 1

                 Else

                     notFound = False

                 End If

             End While

             putCharAtPos(abcStr, i, Convert.ToChar(Convert.ToByte(abcStr.Chars(i)) + 1))

             nextAbc()

        Else

             Write(lastabcStr)

        End If

    End Sub

    Sub Main()

        abcStr = minChar

        For i As Integer = 1 To len

             lastabcStr += maxChar

        Next

        nextAbc()

        Beep(100, 2000)

    End Sub