XE3随笔9：使用不同的数据类型标记数组

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

//使用 Byte、Word、Boolean 标记数组
procedure TForm1.Button1Click(Sender: TObject);
var
  arr1: array[Byte] of Integer;
  arr2: array[Word] of Integer;
  arr3: array[Boolean] of Integer;
begin
  ShowMessage(IntToStr(Length(arr1))); {256}
  arr1[Low(arr1)]  := 11;
  arr1[High(arr1)] := 22;
  ShowMessageFmt(‘%d, %d‘, [arr1[0], arr1[255]]); {11, 22}

  ShowMessage(IntToStr(Length(arr2))); {65536}
  arr2[0]  := 33;
  arr2[65535] := 44;
  ShowMessageFmt(‘%d, %d‘, [arr2[Low(arr2)], arr2[High(arr2)]]); {33, 44}

  ShowMessage(IntToStr(Length(arr3))); {2}
  arr3[False] := 55;
  arr3[True]  := 66;
  ShowMessageFmt(‘%d, %d‘, [arr3[Low(arr3)], arr3[High(arr3)]]); {55, 66}
end;

//使用 "子界" 标记数组
procedure TForm1.Button2Click(Sender: TObject);
type
  TC = ‘a‘..‘z‘;
var
  arr: array[TC] of Integer;
  n1,n2,n3: Integer;
begin
  ShowMessage(IntToStr(Length(arr))); {26}
  arr[‘a‘] := 11;
  arr[‘b‘] := 22;
  arr[‘z‘] := 33;

  n1 := arr[Chr(97)];
  n2 := arr[‘abc‘[2]];
  n3 := arr[‘z‘];

  ShowMessageFmt(‘%d,%d,%d‘, [n1,n2,n3]); {11,22,33}
end;

//使用 "枚举" 标记数组
procedure TForm1.Button3Click(Sender: TObject);
type
  TMyEnum = (A, B, C, D);
var
  arr: array[TMyEnum] of Integer;
  i: Integer;
begin
  arr[A] := 11;
  arr[B] := 22;
  arr[C] := 33;
  arr[D] := 44;

  for i in arr do ShowMessage(IntToStr(i)); { 11/22/33/44 }
end;

//还是使用 "枚举" 标记数组
procedure TForm1.Button4Click(Sender: TObject);
type
  TMyEnum = (X=1, Y=3, Z=5);
var
  arr: array[TMyEnum] of Integer;
  i,n1,n2,n3: Integer;
begin
  arr[X] := 11;
  arr[Y] := 22;
  arr[Z] := 33;

  i := 1; n1 := arr[TMyEnum(i)];
  i := 3; n2 := arr[TMyEnum(i)];
  i := 5; n3 := arr[TMyEnum(i)];

  ShowMessageFmt(‘%d,%d,%d‘, [n1,n2,n3]); {11,22,33}
end;

end.