Imports System
Public Class SortAlphaNumeric
'
' We want to sort characters in this strict order:
' 1. lowercase letters (a–z)
' 2. uppercase letters (A–Z)
' 3. odd digits (1,3,5,7,9)
' 4. even digits (0,2,4,6,8)
'
' Strategy:
' ---------
' Assign each character a "category rank" and sort by:
' (category rank, natural character order)
'
' VB.NET allows custom sorting using Array.Sort with a Comparison(Of T).
'
' Returns category rank for sorting.
' Lower rank = comes earlier.
Shared Function Category(c As Char) As Integer
If c >= "a"c AndAlso c <= "z"c Then Return 0 ' lowercase
If c >= "A"c AndAlso c <= "Z"c Then Return 1 ' uppercase
If Char.IsDigit(c) Then
Dim d As Integer = Convert.ToInt32(c) - Convert.ToInt32("0"c)
If d Mod 2 = 1 Then
Return 2 ' odd digits
Else
Return 3 ' even digits
End If
End If
Return 4 ' fallback (should not happen for alphanumeric input)
End Function
' Custom comparator for sorting characters
Shared Function CompareChars(a As Char, b As Char) As Integer
Dim ca As Integer = Category(a)
Dim cb As Integer = Category(b)
If ca <> cb Then
Return ca - cb ' sort by category first
End If
Return Convert.ToInt32(a) - Convert.ToInt32(b) ' tie-breaker: natural order
End Function
Public Shared Sub Main()
Dim s As String = "a2B3cD8f1Z0"
' Convert string to array of chars
Dim arr() As Char = s.ToCharArray()
' Sort using custom comparator
Array.Sort(arr, Function(a, b) CompareChars(a, b))
' Build result string
Dim result As String = New String(arr)
Console.WriteLine("Sorted result: " & result)
End Sub
End Class
'
' run:
'
' Sorted result: acfBDZ13028
'
