Delphi Write TResourceStream into TStream - delphi

Question

I have embedded an exe file in Resorce file.
when I just Use Stream.SaveToFile('test.exe'); everything works fine,produced exe file works with no error. but when i try to Stream.SaveToStream(Stin); , I get error " Stream write error " . what's wrong with my code ?
var
list: TStringList;
Stream: TResourceStream;
Stin, Stout: TStream;
MemStream: TMemoryStream;
begin
Stream := TResourceStream.Create(HInstance, 'phprogram' , RT_RCDATA);
try
Stin := TStream.Create;
Stout := TStream.Create;
Stream.Position := 0;
Stream.SaveToStream(Stin);
EnDecryptStream(Stin, Stout, 2913);
MemStream.LoadFromStream(Stout);
MemStream.SaveToFile('test.exe');
//Stream.SaveToFile('test.exe');
finally
Stream.Free;
end;
end;
Edited :
Thanks to David ... I changed my code and it worked fine :
var
Stream: TResourceStream;
MemStream: TMemoryStream;
begin
Stream := TResourceStream.Create(HInstance, 'testres' , RT_RCDATA);
MemStream := TMemoryStream.Create;
try
EnDecryptStream(Stream, MemStream, 2913);
MemStream.SaveToFile('test.exe');
finally
MemStream.Free;
Stream.Free;
end;
end;

Answer 1

TStream is an abstract class. You must not instantiate instances of TStream. You must always instantiate a concrete class derived from TStream, such as TFileStream, TMemoryStream, TStringStream, etc.
Furthermore, you use MemStream without initialising it.
It looks like you need to do something like this:
Create the resource stream.
Create a memory stream.
Call EnDecryptStream providing the resource stream as input and the memory stream as output.
Call SaveToFile on the memory stream to save it.
Or even simpler:
Create the resource stream.
Create a file stream.
Call EnDecryptStream providing the resource stream as input and the file stream as output.
One of the most common anti-patterns that we see on Stack Overflow is the excessive use of the memory stream. You appear to want to write to a file, so why not cut out the memory stream, and go straight to the file.
I don't particularly want to write any code here because we can only see a small part of the picture here, and any code that I would write would likely be wrong.
I suspect that you have not enabled compiler warnings and hints, or are perhaps ignoring them. Don't do that. Enable warnings and hints, and heed them.