Delphi 2010 中的泛型數組
2010已發佈很長時間了,口碑還不錯,準備用它開發下一項目,但對泛型等新東西的認識還不夠,就搜了一下,發現下面這篇文章,還不錯,你們一塊兒補補課吧!指針
C++中的模板、C#等語言中泛型技術,給許多操做不一樣類型數據的軟件人員提供了一個很好的方法。其類型的「可變」性,讓許多用過的軟件人員所心喜。可是在Delphi 2009之前的版本中,是歷來沒有的。讓許多不會用Delphi中TList的人員,大大的抱怨。若是用好Delphi中TList,其可用性,我我的認爲,比其它語言中的泛型好用不少(固然對指針的應用和內存的分配、釋放不瞭解的人除外)。orm
自從Delphi 2009的發佈,給許多喜歡用泛型技術的軟件人員,提供了方便。因爲Delphi 2009不太穩定,也沒有過多的去用其泛型技術。Delphi 2010發佈以來,出現許多「Delphi 2010初體驗,是時候拋棄Delphi 7了」的話語的滿天飛,讓我想一看其究竟。隊列
閒話少說,Delphi 2010的泛型單元Generics.Defaults、Generics.Collections;重點仍是Generics.Collections單元,其中有TArray泛型類、TList<T>(列表的泛型)、TQueue<T>(隊列的泛型)、TStack<T> (棧的泛型)、TDictionary<TKey,TValue> (Hash Table哈希表的泛型)及其上述泛型所對應的TObject的泛型,很是普遍。內存
簡單的泛型類應用:(轉)開發
-----------------------------------------------------------------------------------------------同步
unit Unit1;string
interfaceit
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;io
type
TForm1 = class(TForm)
Memo1: TMemo;
Edit1: TEdit;
Edit2: TEdit;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 泛型容器單元}
var
Dictionary: TDictionary<Cardinal,string>;
{定義一個泛型 TDictionary 類, 指定有 Cardinal、string 構成}
{創建}
procedure TForm1.FormCreate(Sender: TObject);
begin
Dictionary := TDictionary<Cardinal,string>.Create;
Memo1.Clear;
Button1.Caption := Button1.Caption + ' 添加';
Button2.Caption := Button2.Caption + ' 刪除';
Button3.Caption := Button3.Caption + ' 嘗試取值';
Button4.Caption := Button4.Caption + ' 清空';
Edit1.Clear;
Edit2.Clear;
Edit1.NumbersOnly := True;
end;
{釋放}
procedure TForm1.FormDestroy(Sender: TObject);
begin
Dictionary.Free;
end;
{添加}
procedure TForm1.Button1Click(Sender: TObject);
var
key: Cardinal;
value: string;
str: string;
k,v: Boolean;
begin
key := StrToIntDef(Edit1.Text, 0);
value := Edit2.Text;
if value = '' then value := 'Null';
k := Dictionary.ContainsKey(key); {Key 是否存在}
v := Dictionary.ContainsValue(value); {Value 是否存在}
if not k then
begin
Dictionary.Add(key, value);
Memo1.Lines.Add(Format('%d=%s', [key, value])); {同步顯示}
end;
if k and not v then
begin
str := Format('key 已存在: %d=%s; 是否修改其值?', [key, Dictionary[key]]);
if MessageBox(0, PChar(str), '提示', MB_OKCANCEL or MB_ICONQUESTION) = mrOk then
begin
//Dictionary[key] := value; {Dictionary[key] = Dictionary.Item[key]}
Dictionary.AddOrSetValue(key, value); {也可以使用上一句}
Memo1.Lines.Values[IntToStr(key)] := value; {同步顯示}
end;
end;
if k and v then
begin
str := Format('%d=%s 已存在, 不能重複添加', [key, value]);
MessageBox(0, PChar(str), '錯誤', MB_OK + MB_ICONHAND);
end;
Text := IntToStr(Dictionary.Count);
end;
{刪除: Remove}
procedure TForm1.Button2Click(Sender: TObject);
var
key: Integer;
i: Integer;
begin
key := StrToIntDef(Edit1.Text, 0);
if not Dictionary.ContainsKey(key) then
begin
ShowMessageFmt('key: %d 不存在', [key]);
Exit;
end;
Dictionary.Remove(key);
Text := IntToStr(Dictionary.Count);
{同步顯示}
i := Memo1.Lines.IndexOfName(IntToStr(key));
if i > -1 then Memo1.Lines.Delete(i);
end;
{嘗試取值: TryGetValue}
procedure TForm1.Button3Click(Sender: TObject);
var
key: Integer;
value: string;
begin
key := StrToIntDef(Edit1.Text, 0);
if Dictionary.TryGetValue(key, value) then
ShowMessageFmt('key: %d 已存在, 其值是: %s', [key, value])
else
ShowMessageFmt('key: %d 不存在', [key])
end;
{清空: Clear}
procedure TForm1.Button4Click(Sender: TObject);
begin
Dictionary.Clear;
Text := IntToStr(Dictionary.Count);
Memo1.Clear; {同步顯示}
end;
end.
--------------------------------------------------------------------------------
自定義泛型應用:(轉)
--------------------------------------------------------------------------------
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Memo1: TMemo;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
Button5: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Button4Click(Sender: TObject);
procedure Button5Click(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
type
TArr<T> = array[0..9] of T; {定義一個泛型數組}
{雖然你們習慣用 T 來泛指其餘類型, 但使用其餘合法的標識符也是能夠的}
{用做 Integer}
procedure TForm1.Button1Click(Sender: TObject);
var
Arr: TArr<Integer>;
i: Integer;
begin
for i := Low(Arr) to High(Arr) do
Arr[i] := i * i;
Memo1.Clear;
for i := Low(Arr) to High(Arr) do
Memo1.Lines.Add(Format('Arr[%d] = %d', [i, Arr[i]]));
end;
{用做 string}
procedure TForm1.Button2Click(Sender: TObject);
var
Arr: TArr<string>;
i: Integer;
begin
for i := Low(Arr) to High(Arr) do
Arr[i] := StringOfChar(Char(i+97), 3);
Memo1.Clear;
for i := Low(Arr) to High(Arr) do
Memo1.Lines.Add(Format('Arr[%d] = %s', [i, Arr[i]]));
end;
{用做 Single}
procedure TForm1.Button3Click(Sender: TObject);
var
Arr: TArr<Single>;
i: Integer;
begin
for i := Low(Arr) to High(Arr) do
Arr[i] := 100 / (i+1);
Memo1.Clear;
for i := Low(Arr) to High(Arr) do
Memo1.Lines.Add(Format('Arr[%d] = %f', [i, Arr[i]]));
end;
{用做記錄 TPoint}
procedure TForm1.Button4Click(Sender: TObject);
var
Arr: TArr<TPoint>;
i: Integer;
begin
for i := Low(Arr) to High(Arr) do
Arr[i] := Point(i, i*2);
Memo1.Clear;
for i := Low(Arr) to High(Arr) do
Memo1.Lines.Add(Format('Arr[%d] = (%d,%d)', [i, Arr[i].X, Arr[i].Y]));
end;
{用做類 TButton}
procedure TForm1.Button5Click(Sender: TObject);
var
Arr: TArr<TButton>;
i: Integer;
begin
for i := Low(Arr) to High(Arr) do
begin
Arr[i] := TButton.Create(Self);
Arr[i].Name := Concat('Btn', IntToStr(i+1));
end;
Memo1.Clear;
for i := Low(Arr) to High(Arr) do
Memo1.Lines.Add(Format('Arr[%d] is %s', [i, Arr[i].Name]));
end;
end.