(4)Delphi 2009 之 TStringBuilder 类[2]: Append 与 AppendFormat

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所属分类:[开发技巧]

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;
    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}

//TStringBuilder.Append 可以添加几乎所有数据类型, 甚至是对象
procedure TForm1.Button1Click(Sender: TObject);
var
  sb1,sb2: TStringBuilder;
  ver: Cardinal;
begin
  sb1 := TStringBuilder.Create;
  sb2 := TStringBuilder.Create;

  sb1.Append('Delphi ');
  ver := 2009;
  sb1.Append(ver);
  ShowMessage(sb1.ToString); { 2009}

  sb2.Append(sb1);
  {换行}
  sb2.AppendLine;
  sb2.Append(Self);
  ShowMessage(sb2.ToString); {Delphi 2009
                              TForm1}

  sb1.Free;
  sb2.Free;
end;

//TStringBuilder.Append 截取字符数组和字符串
procedure TForm1.Button2Click(Sender: TObject);
const
  CharArr: array[0..6] of Char = ('A','B','C','D','E','F','G');
  Str = 'ABCDEFG';
var
  sb: TStringBuilder;
begin
  sb := TStringBuilder.Create;
  sb.Append(CharArr, 2, 3);
  ShowMessage(sb.ToString); {CDE}

  {清空}
  sb.Length := 0;

  sb.Append(Str, 2, 3);
  ShowMessage(sb.ToString); {CDE}

  sb.Free;
end;

//TStringBuilder.Append 添加指定数目的字符
procedure TForm1.Button3Click(Sender: TObject);
var
  sb: TStringBuilder;
begin
  sb := TStringBuilder.Create;
  sb.Append('A', 10);
  ShowMessage(sb.ToString); {AAAAAAAAAA}
  sb.Free;
end;

//TStringBuilder.Append 试试其他数据类型
procedure TForm1.Button4Click(Sender: TObject);
var
  sb: TStringBuilder;
  b: Boolean;
  r: Real;
begin
  sb := TStringBuilder.Create;

  b := True;
  sb.Append(b);
  sb.AppendLine;
 
; b := not b;
  sb.Append(b);
  sb.AppendLine;

  r := 100/3;
  sb.Append(r);

  ShowMessage(sb.ToString); {True
                             False
                             33.3333333333333}

  sb.Free;
end;

//TStringBuilder.AppendFormat 的使用和 Format 函数是一样的
procedure TForm1.Button5Click(Sender: TObject);
var
  sb: TStringBuilder;
begin
  sb := TStringBuilder.Create;
  sb.AppendFormat('%s %d', ['Delphi', 2009]);
  ShowMessage(sb.ToString); {Delphi 2009}
  sb.Free;
end;

end.
 

200809181145445663.rar

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