如何拷贝文件流中的部分数据呢? 例子如下

Question

我想拷贝文件ttt.exe文件中的数据,从200开始到640,如何做呢?
var
fileok:TMemoryStream;
newfile:TMemoryStream;
begin
    fileok:=TMemoryStream.Create;
    fileok.LoadFromFile('d:\ttt.exe');
    fileok.Position:=200;
    newfile:=TMemoryStream.Create;
    newfile.Size:=0;
        //请问如果拷贝fileok文件流,从200开始拷贝640  ???????????????????????????????
    newfile.SaveToFile('d:\chenhui.ico');
    newfile.free;
    fileok.free;
end;

Answer 1

var
  fileok:TMemoryStream;
  newfile:TMemoryStream;
begin
  fileok:=TMemoryStream.Create;
  fileok.LoadFromFile('d:\ttt.exe');
  newfile:=TMemoryStream.Create;
  newfile.Write(PBYTE(Integer(fileok.Memory)+200)^, 640);
  newfile.SaveToFile('c:\chenhui.ico');
  newfile.free;
  fileok.free;
end;

Answer 2

fileok.Position:=200;
newfile:=TMemoryStream.Create;
//newfile.Size:=0;//不必
newFile.CopyFrom(fileok,640-200);
newfile.SaveToFile('d:\chenhui.ico');