unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Button1: TButton; procedure Button1Click(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} //TStringBuilder.ToString 可以带参数 procedure TForm1.Button1Click(Sender: TObject); var sb: TStringBuilder; begin sb := TStringBuilder.Create('123456789'); ShowMessage(sb.ToString); {123456789} ShowMessage(sb.ToString(3, 4)); {4567} sb.Free; end; end.