泛型排序器 TComparer

测试代码文件:

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Memo1: TMemo;

    Memo2: TMemo;

    Button1: TButton;

    Button2: TButton;

    Button3: TButton;

    Button4: TButton;

    Button5: TButton;

    Button6: TButton;

    Button7: TButton;

    Button8: TButton;

    Button9: TButton;

    Button10: TButton;

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

    procedure Button3Click(Sender: TObject);

    procedure Button4Click(Sender: TObject);

    procedure Button5Click(Sender: TObject);

    procedure Button6Click(Sender: TObject);

    procedure Button7Click(Sender: TObject);

    procedure Button8Click(Sender: TObject);

    procedure Button9Click(Sender: TObject);

    procedure Button10Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses Generics.Collections, Generics.Defaults; {必需的泛型单元}



//构建由 10 个整数组成的动态数组, 然后排序

procedure TForm1.Button1Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

begin

  {构建动态数组}

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  {显示排序前}

  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  {排序}

  TArray.Sort<Integer>(arr); {它可以有 1个、2个、4个参数, 这里只用了一个参数, 其他是默认参数}



  {显示排序结果}

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

end;



// TArray.Sort 的第二个参数是 IComparer<T> 类型, 其默认值是: TComparer<T>.Default

procedure TForm1.Button2Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

begin

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  {使用了排序器的默认值排序, 这和忽略这个参数是一样的}

  TArray.Sort<Integer>(arr, TComparer<Integer>.Default);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

end;



//同上两例, 变通了一下写法

procedure TForm1.Button3Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

  Comparer: IComparer<Integer>;

begin

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  Comparer := TComparer<Integer>.Default;

  TArray.Sort<Integer>(arr, Comparer);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

end;



// TArray.Sort 的后面两个参数可以指定排序范围:

procedure TForm1.Button4Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

  Comparer: IComparer<Integer>;

begin

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  Comparer := TComparer<Integer>.Default;

  {这里指定从第 1 个元素开始, 只给 3 个元素排序}

  TArray.Sort<Integer>(arr, Comparer, 0, 3);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

end;



//如果要倒排序, 可以建立自己的排序器, 下面就是先构建并实现了一个 TMyComparer, 然后调用:

type

  TMyComparer = class(TComparer<Integer>)

  public

    function Compare(const Left, Right: Integer): Integer; override;

  end;



{ TMyComparer }

function TMyComparer.Compare(const Left, Right: Integer): Integer;

begin

  Result := Right - Left;

end;



procedure TForm1.Button5Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

  Comparer: TMyComparer;

begin

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  Comparer := TMyComparer.Create;

  TArray.Sort<Integer>(arr, Comparer);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

  Comparer.Free;

end;





// 也可以用 TComparer<T>.Construct 方法, 通过一个 TComparison 格式的函数构建排序器, 这样简单一些

function MyFunc1(const Left, Right: Integer): Integer;

begin

  Result := Right - Left;

end;



procedure TForm1.Button6Click(Sender: TObject);

var

  arr: array of Integer;

  i: Integer;

  Comparer: IComparer<Integer>;

begin

  Randomize;

  for i := 0 to 9 do begin

    SetLength(arr, Length(arr)+1);

    arr[i] := Random(10);

  end;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(IntToStr(arr[i]));



  Comparer := TComparer<Integer>.Construct(MyFunc1);

  TArray.Sort<Integer>(arr, Comparer);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(IntToStr(arr[i]));

end;





//如果是给自定义类型的元素排序, 只能是自建排序器

type

  TPerson = record

    name: string;

    age: Word;

  end;



function MyFunc2(const Left, Right: TPerson): Integer;

begin

  Result := Left.age - Right.age;

end;



procedure TForm1.Button7Click(Sender: TObject);

var

  arr: array of TPerson;

  i: Integer;

  Comparer: IComparer<TPerson>;

begin

  SetLength(arr, 4);

  arr[0].name := 'AA'; arr[0].age := 22;

  arr[1].name := 'BB'; arr[1].age := 33;

  arr[2].name := 'CC'; arr[2].age := 44;

  arr[3].name := 'DD'; arr[3].age := 11;



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do

    Memo1.Lines.Add(Format('%s : %d', [arr[i].name, arr[i].age]));



  Comparer := TComparer<TPerson>.Construct(MyFunc2);

  TArray.Sort<TPerson>(arr, Comparer);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do

    Memo2.Lines.Add(Format('%s : %d', [arr[i].name, arr[i].age]));

end;



// TStringComparer.Ordinal 是官方实现的用于 string 的排序器, 可直接使用.

//但它好像有问题(Delphi 2010 - 14.0.3513.24210), 以后的版本应该能改过来.

procedure TForm1.Button8Click(Sender: TObject);

var

  arr: array of string;

  i: Integer;

begin

  SetLength(arr, 4);

  arr[0] := '222';

  arr[1] := '111';

  arr[2] := 'bbb';

  arr[3] := 'aaa';



  Memo1.Clear;

  for i := 0 to Length(arr) - 1 do Memo1.Lines.Add(arr[i]);



  TArray.Sort<string>(arr, TStringComparer.Ordinal);

  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(arr[i]);

end;



//下面是实现字符串数组的到排序

function MyComparerFunc(const s1,s2: string): Integer;

begin

  Result := CompareText(s2, s1);

  //Result := -CompareText(s1, s2); {或者这样}

end;



procedure TForm1.Button9Click(Sender: TObject);

var

  arr: array of string;

  i: Integer;

  Comparer: IComparer<string>;

begin

  Memo1.Clear;

  Memo1.Lines.CommaText := '11,33,22,AAA,CCC,BBB';

  SetLength(arr, Memo1.Lines.Count);

  for i := 0 to Length(arr) - 1 do arr[i] := Memo1.Lines[i];



  Comparer := TComparer<string>.Construct(MyComparerFunc);

  TArray.Sort<string>(arr, Comparer);



  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(arr[i]);

end;



//可以把上一个程序简写为:

procedure TForm1.Button10Click(Sender: TObject);

var

  arr: array of string;

  i: Integer;

  Comparer: IComparer<string>;

begin

  Memo1.Clear;

  Memo1.Lines.CommaText := '11,33,22,AAA,CCC,BBB';

  SetLength(arr, Memo1.Lines.Count);

  for i := 0 to Length(arr) - 1 do arr[i] := Memo1.Lines[i];



  Comparer := TComparer<string>.Construct(

    function (const s1,s2: string): Integer

    begin

      Result := CompareText(s2, s1);

    end);

  TArray.Sort<string>(arr, Comparer);



  Memo2.Clear;

  for i := 0 to Length(arr) - 1 do Memo2.Lines.Add(arr[i]);

end;



end.


 
   

测试窗体文件(之所以附上窗体文件, 是为了再次测试方便):

---

object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 321

  ClientWidth = 318

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  PixelsPerInch = 96

  TextHeight = 13

  object Memo1: TMemo

    Left = 0

    Top = 0

    Width = 89

    Height = 321

    Align = alLeft

    Lines.Strings = (

      'Memo1')

    TabOrder = 0

    ExplicitHeight = 299

  end

  object Button1: TButton

    Left = 120

    Top = 8

    Width = 75

    Height = 25

    Caption = 'Button1'

    TabOrder = 1

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 120

    Top = 39

    Width = 75

    Height = 25

    Caption = 'Button2'

    TabOrder = 2

    OnClick = Button2Click

  end

  object Button3: TButton

    Left = 120

    Top = 70

    Width = 75

    Height = 25

    Caption = 'Button3'

    TabOrder = 3

    OnClick = Button3Click

  end

  object Memo2: TMemo

    Left = 219

    Top = 0

    Width = 99

    Height = 321

    Align = alRight

    Lines.Strings = (

      'Memo2')

    TabOrder = 4

    ExplicitHeight = 299

  end

  object Button4: TButton

    Left = 120

    Top = 101

    Width = 75

    Height = 25

    Caption = 'Button4'

    TabOrder = 5

    OnClick = Button4Click

  end

  object Button5: TButton

    Left = 120

    Top = 132

    Width = 75

    Height = 25

    Caption = 'Button5'

    TabOrder = 6

    OnClick = Button5Click

  end

  object Button6: TButton

    Left = 120

    Top = 163

    Width = 75

    Height = 25

    Caption = 'Button6'

    TabOrder = 7

    OnClick = Button6Click

  end

  object Button7: TButton

    Left = 120

    Top = 194

    Width = 75

    Height = 25

    Caption = 'Button7'

    TabOrder = 8

    OnClick = Button7Click

  end

  object Button8: TButton

    Left = 120

    Top = 225

    Width = 75

    Height = 25

    Caption = 'Button8'

    TabOrder = 9

    OnClick = Button8Click

  end

  object Button9: TButton

    Left = 120

    Top = 256

    Width = 75

    Height = 25

    Caption = 'Button9'

    TabOrder = 10

    OnClick = Button9Click

  end

  object Button10: TButton

    Left = 120

    Top = 287

    Width = 75

    Height = 25

    Caption = 'Button10'

    TabOrder = 11

    OnClick = Button10Click

  end

end