(*//

标题:充分利用pascal字符串类型

说明:和PChar不同,string可以保存#0字符在其中;示例文件、内存流字符串之间转换

设计:Zswang

日期:2002-01-25

支持:wjhu111@21cn.com

//*)

///////Begin Source

function StringToFile(mString: string; mFileName: TFileName): Boolean;

{ 返回字符串保存到文件是否成功 }

var

 vFileChar: file of Char;

 I: Integer;

begin

 {$I-}

 AssignFile(vFileChar, mFileName);

 Rewrite(vFileChar);

 for I := 1 to Length(mString) do Write(vFileChar, mString[I]);

 CloseFile(vFileChar);

 {$I+}

 Result := (IOResult = 0) and (mFileName <> '');

end; { StringToFile }

function FileToString(mFileName: TFileName): string;

{ 返回从文件载入字符串 }

var

 vFileChar: file of Char;

 vChar: Char;

begin

 Result := '';

 {$I-}

 AssignFile(vFileChar, mFileName);

 Reset(vFileChar);

 while not Eof(vFileChar) do begin

   Read(vFileChar, vChar);

   Result := Result + vChar;

 end;

 CloseFile(vFileChar);

 {$I+}

end; { FileToString }

function StreamToString(mStream: TStream): string;

{ 将内存流转换成字符串 }

var

 I: Integer;

begin

 Result := '';

 if not Assigned(mStream) then Exit;

 SetLength(Result, mStream.Size);

 for I := 0 to Pred(mStream.Size) do try

   mStream.Position := I;

   mStream.Read(Result[Succ(I)], 1);

 except

   Result := '';

 end;

end; { StreamToString }

function StringToStream(mString: string; mStream: TStream): Boolean;

{ 返回将字符串保存到内存流是否成功 }

var

 I: Integer;

begin

 Result := True;

 try

   mStream.Size := 0;

   mStream.Position := 0;

   for I := 1 to Length(mString) do mStream.Write(mString[I], 1);

 except

   Result := False;

 end;

end; { StringToStream }

///////End Source

///////Begin Demo

procedure TForm1.Button1Click(Sender: TObject);

var

 vMemoryStream: TMemoryStream;

begin

 Memo1.Text := FileToString('C:\WINDOWS\Desktop\1.txt');

 vMemoryStream := TMemoryStream.Create;

 try

   Memo1.Lines.SaveToStream(vMemoryStream);

   Memo2.Text := StreamToString(vMemoryStream);

 finally

   vMemoryStream.Free;

 end;

end;

procedure TForm1.Button2Click(Sender: TObject);

var

 vMemoryStream: TMemoryStream;

begin

 StringToFile(Memo2.Text, 'C:\WINDOWS\Desktop\1.txt');

 vMemoryStream := TMemoryStream.Create;

 try

   StringToStream(Memo2.Text, vMemoryStream);

   vMemoryStream.Position := 0;

   Memo1.Lines.LoadFromStream(vMemoryStream);

 finally

   vMemoryStream.Free;

 end;

end;

///////End Demo