tmemorystream内存合并出错， 帮忙排错：)

Question

procedure TForm1.Button1Click(Sender: TObject);
var
          strmSource,strmDest:TMemoryStream;
          f1, f2:string;
        begin
f1 := 'c:\a.txt';
f2 := 'c:\b.txt';
          //先读f1
          strmSource:=TMemoryStream.Create;
          strmSource.loadfromfile(f1);
          //拷贝到strmdest
          strmDest:=TMemoryStream.Create;
          strmDest.copyfrom(strmSource,strmSource.size);
          strmSource.clear;
          //再读f1
          strmSource.loadfromfile(f2);
          //拷贝到strmdest
          strmDest.seek(strmDest.size,soFromBeginning);
          strmDest.copyfrom(strmSource,strmSource.size);
          strmSource.free;
          //这时strmDest里面便是两个文件合并后的内容了.将它保存为文件
          strmDest.SaveToFile('c:\ab.txt');
          strmDest.free;
        end;
procedure TForm1.Button2Click(Sender: TObject);
var
          strmSource,strmDest:TMemoryStream;
          f1, f2:string;
        begin
f1 := 'c:\a.txt';
f2 := 'c:\b.txt';
          //先读f1
          strmSource:=TMemoryStream.Create;
          strmSource.write(f1[1], length(f1));
          //拷贝到strmdest
          strmDest:=TMemoryStream.Create;
          strmDest.copyfrom(strmSource,strmSource.size); //*********这里出现读错误， 何解？
          strmSource.clear;
          //再读f1
          strmSource.write(f2[1], length(f2));
          //拷贝到strmdest
          strmDest.seek(strmDest.size,soFromBeginning);
          strmDest.copyfrom(strmSource,strmSource.size);
          strmSource.free;
          //这时strmDest里面便是两个文件合并后的内容了.将它保存为文件
          strmDest.SaveToFile('c:\ab.txt');
          strmDest.free;
        end;
end.

Answer 1

var
  strmSource,strmDest:TMemoryStream;
  f1, f2:string;
begin
  f1 := 'c:\a.txt';
  f2 := 'c:\b.txt';
          //先读f1
  strmSource:=TMemoryStream.Create;
  strmSource.write(f1[1], length(f1));
  //拷贝到strmdest
  strmSource.Position := 0;  //加上这句  strmDest:=TMemoryStream.Create;
  strmDest.copyfrom(strmSource,strmSource.size); //*********这里出现读错误， 何解？
  strmSource.clear;
  //再读f1
  strmSource.write(f2[1], length(f2));  strmSource.Position := 0;  //还有这句
  //拷贝到strmdest
  strmDest.seek(strmDest.size,soFromBeginning);
  strmDest.copyfrom(strmSource,strmSource.size);
  strmSource.free;
  //这时strmDest里面便是两个文件合并后的内容了.将它保存为文件
  strmDest.SaveToFile('c:\ab.txt');
  strmDest.free;
end;

Answer 2

呵呵，原来load的时候自动设置位置的啊，
procedure TMemoryStream.LoadFromStream(Stream: TStream);
var
  Count: Longint;
begin
  Stream.Position := 0;
  Count := Stream.Size;
  SetSize(Count);
  if Count <> 0 then Stream.ReadBuffer(FMemory^, Count);
end;