摘要：
');//------------------- 3.使用CreateFileMapping创建刚使用FileOpen--//tryFFileSize:=GetFileSize创建的HANDLE文件映射对象；FMapHandle:=CreateFileMapping；如果FMapHandle=0，则引发异常。创建（'创建内存映射文件失败！
unit filemap; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; const fileName = 'myTest.txt'; type TForm1 = class(TForm) btnUpper: TButton; btnLower: TButton; txtContent: TMemo; Label1: TLabel; btnClose: TButton; procedure FormCreate(Sender: TObject); procedure btnUpperClick(Sender: TObject); procedure btnLowerClick(Sender: TObject); procedure btnCloseClick(Sender: TObject); private { Private declarations } public UCase:Boolean; procedure ChangeFileCase; end; var Form1: TForm1; implementation {$R *.dfm} // 全文中的txtContent.Lines.LoadFromFile(fileName)其目的只是为了显示文件修改结果 procedure TForm1.FormCreate(Sender: TObject); begin txtContent.Clear(); txtContent.Lines.LoadFromFile(fileName); //缺省将其转变为大写 UCase := True; end; procedure TForm1.btnUpperClick(Sender: TObject); begin UCase := true; ChangeFileCase; end; procedure TForm1.btnLowerClick(Sender: TObject); begin UCase := false; ChangeFileCase; end; procedure Tform1.ChangeFileCase;//这个是本示例文件的核心运算部分 var FFileHandle : THandle; FMapHandle : THandle; FFileSize : Integer; FData : PByte; PData : PChar; begin //-------------------1 判断文件是否存在----------------------// if not FileExists(fileName) then raise Exception.Create('文件不存在!') else //-------------------2 使用FileOpen获取一个文件HANDLE--------// FFileHandle := FileOPen(fileName,fmOPenReadWrite); //如果创建文件失败，就抛出一个异常 if FFileHandle = INVALID_HANDLE_VALUE then raise Exception.Create('打开或创建文件失败！'); //-------------------3 使用CreateFileMapping创建一个刚才用FileOpen创建的HANDLE的文件映射对象-- -// try FFileSize := GetFileSize(FFileHandle,nil); FMapHandle := CreateFileMapping(FFileHandle,nil,PAGE_READWRITE,0,FFileSize,nil); if FMapHandle = 0 then raise Exception.Create('创建内存映射文件失败！'); finally CloseHandle(FFileHandle); end; //-------------------4 使用MapViewOfFile创建一个CreateFileMapping建立的HANDLE的映射文件的视图到 进程的地址空间------// try FData := MapViewOfFile(FMapHandle,FILE_MAP_ALL_ACCESS,0,0,FFileSize); if FData = nil then raise Exception.Create('映射文件失败!'); finally CloseHandle(FMapHandle); end; //-------------------5 对MapViewOfFile返回的指针做相应的运算操作------// try PData := PChar(FData); inc(PData,FFileSize); PData^ := #0; if UCase then StrUpper(PChar(FData)) else StrLower(PChar(FData)); finally //-------------------6 取消文件视图的映射------// UnmapViewOfFile(FData); end; txtContent.Lines.Clear(); txtContent.Lines.LoadFromFile(fileName); end; procedure TForm1.btnCloseClick(Sender: TObject); begin Form1.Close(); end; end. { //-------------------------------------------------------// 在做指针具体运算时，可以采用这样直接获取该指针处的某一类型的值 procedure TForm1.Button1Click(Sender: TObject); var i: Integer; p: Pointer; begin i := 12345678; p := @i; showmessage(inttostr(integer(p))); //俺的电脑上1242664,这是一个地址 showmessage(inttostr(Pinteger(p)^)); //12345678 showmessage(inttostr(PWord(p)^)); //24910 end; Pinteger(p)^表示指针P处取得一个Integer值 PWord(p)^表示指针P处取得一个Word值
在windows.pas和system.pas中还定义了很多指针类型如下 PInteger = ^Integer; {$NODEFINE PInteger} { defined in sysmac.h } PCardinal = ^Cardinal; PWord = ^Word; PSmallInt = ^SmallInt; {$NODEFINE PSmallInt} { defined in sysmac.h } {$POINTERMATH ON} PByte = ^Byte; {$NODEFINE PByte} { defined in sysmac.h } {$POINTERMATH OFF} PShortInt = ^ShortInt; {$NODEFINE PShortInt} { defined in sysmac.h } PInt64 = ^Int64; {$NODEFINE PInt64} { defined in sysmac.h } PUInt64 = ^UInt64; PLongWord = ^LongWord; {$NODEFINE PLongWord} { defined in sysmac.h } PSingle = ^Single; {$NODEFINE PSingle} { defined in sysmac.h } PDouble = ^Double; {$NODEFINE PDouble} { defined in sysmac.h } PDate = ^Doub