C# と VB.NET の質問掲示板

Imports System
Imports System.Collections.Generic

Public Structure データ
  Public key1 As String
  Public key2 As String
  Public key3 As String
End Structure

Public Class MultiKeyComp(Of T)
  Implements IComparer(Of T)

  Dim comps() As Comparison(Of T)

  Public Function Compare(ByVal x As T, ByVal y As T) As Integer _
    Implements IComparer(Of T).Compare
    For Each c As Comparison(Of T) In comps
      Dim result As Integer = c(x, y)
      If result <> 0 Then Return result
    Next
    Return 0
  End Function

  Public Sub New(ByVal ParamArray c() As Comparison(Of T))
    comps = c
  End Sub

End Class

Public Class Program

  Shared Function lt1(ByVal x As データ, ByVal y As データ) As Integer
    Return x.key1.CompareTo(y.key1)
  End Function
  Shared Function gt1(ByVal x As データ, ByVal y As データ) As Integer
    Return y.key1.CompareTo(x.key1)
  End Function
  Shared Function lt2(ByVal x As データ, ByVal y As データ) As Integer
    Return x.key2.CompareTo(y.key2)
  End Function
  Shared Function gt2(ByVal x As データ, ByVal y As データ) As Integer
    Return y.key2.CompareTo(x.key2)
  End Function
  Shared Function lt3(ByVal x As データ, ByVal y As データ) As Integer
    Return x.key3.CompareTo(y.key3)
  End Function
  Shared Function gt3(ByVal x As データ, ByVal y As データ) As Integer
    Return y.key3.CompareTo(x.key3)
  End Function
  Shared Function non(ByVal x As データ, ByVal y As データ) As Integer
    Return 0
  End Function

  Public Shared Sub Main()
    Dim N As Integer = 10
    Dim data(N - 1) As データ
    Dim r As New Random()
    For i As Integer = 0 To N - 1
      Dim datum As New データ()
      With datum
        .key1 = r.Next(10).ToString()
        .key2 = r.Next(10).ToString()
        .key3 = r.Next(10).ToString()
      End With
      data(i) = datum
    Next

    Console.WriteLine("ソート前")
    For Each item As データ In data
      Console.WriteLine("{0} {1} {2}", item.key1, item.key2, item.key3)
    Next
    Console.WriteLine()

    ' 昇順,ソートせず,降順　でソートする
    Dim c As New  _
      MultiKeyComp(Of データ)(AddressOf lt1, _
                              AddressOf non, _
                              AddressOf gt3)
    Array.Sort(data, c)

    Console.WriteLine("ソート後")
    For Each item As データ In data
      Console.WriteLine("{0} {1} {2}", item.key1, item.key2, item.key3)
    Next
  End Sub

End Class

>分類と利用されてる環境がちょっと一致しないような…プロジェクトが2005を対象にしたものと考えてよろしいでしょうか？
単純に項目にVB2008がない＆「VB.NET」とあるのでVB2008も含まれる　と考えての選択ではないでしょうか。

もしターゲットが.NETFramework3.5であればLINQ使えば楽です。

Key1の昇順かつKey2の降順で並べてみます


Dim SortedDatas = From n In Datas _
                  Order By n.Key1 Ascending, n.Key2 Descending

For i As Integer = 0 To Datas.Length - 1
    Datas(i) = SortedDatas(i)
Next


ただし構造体メンバーに参照型が含まれると、Forループでのコピー時に
注意が必要です。

おー。
みんないろいろな手を使いますねぇ

DataTableを使うのが楽な気がしますが、私はあまりすきじゃないです。
私ならIComparerを使って比較用のクラスをつくります。


    Public Structure data
        Public key1 As String
        Public key2 As String
        Public key3 As String
    End Structure

    Public Enum SortType
        None
        Ascendant
        Desccendant
    End Enum

    Public Class DataComparer
        Implements IComparer(Of data)
        Private key1sorttype As SortType
        Private key2sorttype As SortType
        Private key3sorttype As SortType

        Public Sub New(ByVal key1sorttype As SortType, ByVal key2sorttype As SortType, ByVal key3sorttype As SortType)
            Me.key1sorttype = key1sorttype
            Me.key2sorttype = key2sorttype
            Me.key3sorttype = key3sorttype
        End Sub

        Public Function Compare(ByVal x As data, ByVal y As data) As Integer Implements System.Collections.Generic.IComparer(Of data).Compare
            Dim r As Integer
            Select Case Me.key1sorttype
                Case SortType.Ascendant
                    r = String.Compare(x.key1, y.key1)
                Case SortType.Desccendant
                    r = -String.Compare(x.key1, y.key1)
            End Select
            If r <> 0 Then Return r
            Select Case Me.key1sorttype
                Case SortType.Ascendant
                    r = String.Compare(x.key2, y.key2)
                Case SortType.Desccendant
                    r = -String.Compare(x.key2, y.key2)
            End Select
            If r <> 0 Then Return r
            Select Case Me.key1sorttype
                Case SortType.Ascendant
                    r = String.Compare(x.key3, y.key3)
                Case SortType.Desccendant
                    r = -String.Compare(x.key3, y.key3)
            End Select
            Return r
        End Function

    End Class

    Public Sub sort(ByVal parameter As data(), ByVal key1sorttype As SortType, ByVal key2sorttype As SortType, ByVal key3sorttype As SortType)
        Array.Sort(parameter, New DataComparer(key1sorttype, key2sorttype, key2sorttype))
    End Sub

こんな感じで。

↓C#らむだ版

using System;

namespace MultiKey_cs {

  /*
   * ぶっちゃけキモはこいつだけ。
   */
  class MultiKeyComp<T> : System.Collections.Generic.IComparer<T> {
    private Comparison<T>[] comps;

    public MultiKeyComp(params Comparison<T>[] c) {
      comps = c;
    }

    public int Compare(T x, T y) {
      int result = 0;
      foreach ( Comparison<T> c in comps ) {
        if ( (result = c(x, y)) != 0 ) break;
      }
      return result;
    }

  }

  public struct データ {
    public string key1;
    public string key2;
    public string key3;
  }

  public class Program {
    public static void Main() {
      int N  = 10;
      データ[] data = new データ[N];
      Random r = new Random();
      for ( int i = 0; i < N; ++i ) {
        データ datum = new データ();
        datum.key1 = r.Next(10).ToString();
        datum.key2 = r.Next(10).ToString();
        datum.key3 = r.Next(10).ToString();
        data[i] = datum;
      }

      Console.WriteLine("ソート前");
      Array.ForEach(data, 
        x => Console.WriteLine("{0} {1} {2}", x.key1, x.key2, x.key3));
      Console.WriteLine();

      Array.Sort(data,
                 new MultiKeyComp<データ>(
                  (x,y) => x.key1.CompareTo(y.key1), // key1:昇順
                  (x,y) => 0,                        // key2:don't care
                  (x,y) => y.key3.CompareTo(x.key3)  // key3:降順
                 )
                );

      Console.WriteLine("ソート後");
      Array.ForEach(data, 
        x => Console.WriteLine("{0} {1} {2}", x.key1, x.key2, x.key3));
      Console.WriteLine();
    }
  }
}