测试字符串写入类: TStringWriter

以前没见过这个类, 它是在 TStringBuilder 的基础上实现的; 使用它可以方便地把各种数据类型写入字符串.

---

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;

    Button5: TButton;

    Button6: TButton;

    Button7: 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);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



// 其 WriteLine、Write 各有写入多种数据类型的重载

procedure TForm1.Button1Click(Sender: TObject);

var

  Writer: TStringWriter;

begin

  Writer := TStringWriter.Create;

  Writer.WriteLine('aaa');

  Writer.WriteLine('bbb');

  ShowMessage(Writer.ToString);

  Writer.Free;



  Writer := TStringWriter.Create;

  Writer.Write('aaa');

  Writer.Write('bbb');

  Writer.WriteLine;

  Writer.Write('ccc');

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//写入 Boolean、Char

procedure TForm1.Button2Click(Sender: TObject);

const

  b1: Boolean = True;

  b2: Boolean = False;

  c1: Char = 'A';

  c2: Char = 'B';

var

  Writer: TStringWriter;

begin

  Writer := TStringWriter.Create;

  Writer.WriteLine(b1);

  Writer.WriteLine(b2);

  Writer.WriteLine(c1);

  Writer.WriteLine(c2);

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//写入整数和浮点数

procedure TForm1.Button3Click(Sender: TObject);

const

  n1 = 1;

  n2 = -1;

  f = 3.14;

var

  Writer: TStringWriter;

begin

  Writer := TStringWriter.Create;

  Writer.WriteLine(n1);

  Writer.WriteLine(n2);

  Writer.WriteLine(f);

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//格式化写入

procedure TForm1.Button4Click(Sender: TObject);

var

  Writer: TStringWriter;

begin

  Writer := TStringWriter.Create;

  Writer.Write('%d + %d = %d', [1,2,3]);

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//写入字符数组

procedure TForm1.Button5Click(Sender: TObject);

var

  Writer: TStringWriter;

  cs: TCharArray;

  i: Integer;

begin

  SetLength(cs, 26);

  for i := 0 to Length(cs) - 1 do cs[i] := Chr(65+i);



  Writer := TStringWriter.Create;

  Writer.WriteLine(cs);

  Writer.WriteLine(cs, 1, 3);

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//写入对象(类名)

procedure TForm1.Button6Click(Sender: TObject);

var

  Writer: TStringWriter;

begin

  Writer := TStringWriter.Create;

  Writer.WriteLine(Self);

  Writer.WriteLine(Sender);

  ShowMessage(Writer.ToString);

  Writer.Free;

end;



//从 TStringBuilder 建立

procedure TForm1.Button7Click(Sender: TObject);

var

  Writer: TStringWriter;

  sb: TStringBuilder;

begin

  sb := TStringBuilder.Create('ABC');



  Writer := TStringWriter.Create(sb);

  Writer.WriteLine;

  Writer.Write(123);

  ShowMessage(Writer.ToString);



  sb.Free;

  Writer.Free;

end;



end.