[fpc-pascal] File handling: the TFileStream or the classical way is faster and more efficient?

[Michael Van Canneyt]

On Mon, 25 May 2015, Géza Kovacs Géza wrote:

> Hi All!
>
> What is the faster and more efficient, using the TFileStream or the
> classical way ("file of byte", or "file") type with
> blockread/blockwrite and the other well-know procedures?
> What is the better, faster on large files?

TFileStream offers more flexibility, but as far as efficiency is concerned : 
I think that will be the same for both approaches.

For example, your first example can be done easier in a single statement:

OutF.CopyFrom(Inf,0);

Michael.

>
> See the two example code below.
>
> Program FileCopy_stream;
> {$mode objfpc} {$H+}
> uses classes,SysUtils;
> var
> 	BytesRead,TotalBytesRead : Int64;
> 	puffer : array [1..1048576] of byte;
> 	InF, OutF : TFileStream;
> begin
> 		TotalBytesRead := 0;
> 		BytesRead := 0;
> 		try
> 			InF:= TFileStream.Create(ParamSTR(1),fmOpenRead);
> 			OutF := TFileStream.Create(ParamSTR(2),fmCreate);
> 				repeat
> 					BytesRead := InF.Read(puffer,sizeof(puffer));
> 					inc(TotalBytesRead, BytesRead);
> 					OutF.Write(puffer,BytesRead);
> 				until (TotalBytesRead = InF.size);
> 			finally
> 			FreeAndNil(InF);
> 			FreeAndNil(OutF);
> 		end;
> end.
>
> Program FileCopy_Classic;
> {$mode objfpc} {$H+}
> var
> 	NumRead, NumWritten : LongInt;
> 	puffer : array [1..1048576] of byte;
> 	InF,OutF : file of byte;
> begin
> 		assign(InF,ParamStr(1));
> 		ReSet(InF);
> 		Assign(OutF,ParamStr(2));
> 		ReWrite(OutF);
> 		repeat
> 			BlockRead(InF,puffer,SizeOf(puffer),NumRead);
> 			BlockWrite(OutF,puffer,NumRead,NumWritten);
> 		until (NumRead = 0);
> 		close(InF);
> 		close(OutF);
> end.
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