[RESOLVED] Vb.net 2010 Sort List(of String) : String with Integer

[MattP]

You'll need to have a Natural Comparison of the strings to get what you're looking for.

Here's a couple of options.

Imports System.Text.RegularExpressions
 
Public Class NaturalComparer
    Implements IComparer(Of String)
 
    Private _pos As Integer
    Private ReadOnly _order As Integer
 
    Public Sub New(Optional Ascending As Boolean = True)
        _order = If(Ascending, 1, -1)
    End Sub
 
    Private Shared Function RegexSplit(ByVal s As String) As String()
        Return Regex.Split(s, "(\d+)", RegexOptions.IgnoreCase)
    End Function
 
    Private Shared Function GetEmptyStrings() As Predicate(Of String)
        Return Function(s) String.IsNullOrEmpty(s)
    End Function
 
    Public Function Compare(x As String, y As String) As Integer Implements IComparer(Of String).Compare
        Dim left As New List(Of String)(RegexSplit(x))
        Dim right As New List(Of String)(RegexSplit(y))
 
        left.RemoveAll(GetEmptyStrings())
        right.RemoveAll(GetEmptyStrings())
 
        _pos = 0
        For Each x In left
            If y.Count > _pos Then
                If Not Decimal.TryParse(x, Nothing) AndAlso Not Decimal.TryParse(right(_pos), Nothing) Then
                    Dim result As Integer = String.Compare(x, right(_pos), True)
                    If result <> 0 Then
                        Return result * _order
                    Else
                        _pos += 1
                    End If
                ElseIf Decimal.TryParse(x, Nothing) AndAlso Not Decimal.TryParse(right(_pos), Nothing) Then
                    Return -1 * _order
                ElseIf Not Decimal.TryParse(x, Nothing) AndAlso Decimal.TryParse(right(_pos), Nothing) Then
                    Return 1 * _order
                Else
                    Dim result = Decimal.Compare(Decimal.Parse(x), Decimal.Parse(right(_pos)))
                    If result = 0 Then
                        _pos += 1
                    Else
                        Return result * _order
                    End If
                End If
            Else
                Return -1 * _order
            End If
        Next
 
        Return _order
    End Function
End Class

Or using Api Methods.

Public Class ApiNaturalComparer
    Implements IComparer(Of String)
 
    Private Class NativeMethods
        Public Declare Unicode Function StrCmpLogicalW Lib "shlwapi.dll" (s1 As String, s2 As String) As Integer
    End Class
 
    Private ReadOnly _order As Integer
 
    Public Sub New(Optional IsAscending As Boolean = True)
        _order = If(IsAscending, 1, -1)
    End Sub
 
    Public Function Compare(x As String, y As String) As Integer Implements IComparer(Of String).Compare
        Return NativeMethods.StrCmpLogicalW(x, y) * _order
    End Function
End Class

Usage example of both options.

Public Class Form1
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim MyList = New List(Of String)({"ob1", "ob5", "ob2", "ob3", "ob33", "ob10", "ob1", "ob11", "ob123", "ob20"})
        'MyList.Sort(New NaturalComparer(True))
        'OutputListBox.Items.AddRange(MyList.ToArray())
 
        MyList.Sort(New ApiNaturalComparer(True))
        OutputListBox.Items.AddRange(MyList.ToArray())
    End Sub
End Class