TStream.Position compared to TStream.Seek

Question

To move the "current byte" pointer in TStream class we can use property Position (e.g. MyStream.Position := 0) or using Seek method (e.g. MyStream.Seek(0, soFromBeginning). The question is, which one is more efficient (aka faster)? (I don't have the source, so I could not check it myself).

So far I always use Seek in positioning that said pointer.

Answer 1

As TStream.Seek is an overloaded function handling 32-Bit or 64-Bit values, it depends on the current stream implementation, which might be the better choice.

For instance TCustomMemoryStream implements the 32-Bit version of Seek(). When you set Position on that stream this will first call the 64-Bit version, which casts the value to a Longint while calling the 32-Bit version. (This will probably change with a 64-Bit version of Delphi!)

On the other hand a THandleStream implements the 64-Bit version of Seek(). When you call Seek() with a 32-Bit value you end up in a quite nasty mechanism calling the 64-Bit version.

My personal advice would be to set Position. At least it will be the better choice in the future.