WinAPI: EqualRect、EqualSid、EqualPrefixSid - 判断一个矩形(或其他结构)是否相等 
unit Unit1;

interface

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

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

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  R1: TRect = (Left:20; Top:20; Right:20; Bottom:20);
  R2: TRect = (Left:20; Top:20; Right:20; Bottom:20);

//EqualRect
procedure TForm1.Button1Click(Sender: TObject);
var
  s1,s2: string;
begin
  ShowMessage(BoolToStr(EqualRect(R1,R2), True));  {True}

  OffsetRect(R2, 10, 10);
  ShowMessage(BoolToStr(EqualRect(R1,R2), True));  {False}
end;

//EqualSid: 它可用于判断所有结构; EqualRect 是专用于 TRect 的.
procedure TForm1.Button2Click(Sender: TObject);
begin
  ShowMessage(BoolToStr(EqualSid(@R1,@R2), True)); {True}

  OffsetRect(R2, 10, 10);
  ShowMessage(BoolToStr(EqualSid(@R1,@R2), True)); {False}
end;

//EqualPrefixSid: 它和 EqualSid 的用法一样, 可能是适用于和服务器联系的.
procedure TForm1.Button3Click(Sender: TObject);
begin
  ShowMessage(BoolToStr(EqualPrefixSid(@R1,@R2), True)); {True}

  OffsetRect(R2, 10, 10);
  ShowMessage(BoolToStr(EqualPrefixSid(@R1,@R2), True)); {False}
end;

end.