Re: implementation question about writing and reading from files

["Francis Crick" <fcrNOSPAMick@fas.harvard.edu>]

I'm still really confused about these calls...anyone willing to offer me
some extra help?

I've been playing around with these calls but i really don't understand what
the parameters mean...obviously File_Type is the file i'm getting, but what
about the Item and Last parameters?  Is Stream_Element a generic type I have
to declare, and if so, how and where do I do that?  If not, how can I ensure
I'm getting the ammount of data out of the file that I want on any platform?

The From param in Read - what does this represent exactly?  from byte #?
from Stream_Element # in the stream?

And also, if I want to use a stream for keeping data in memory, how do i
that?  How do i instantiate a stream that I can just write to and read from
at my leisure?  Also, the data I'm moving is large, and chances are I won't
be using it for much else other than writing back to other file streams, so
how can i make the reading and writing as fast as possible?  Could I make it
read a whole mb in one go as a single unit?

Sorry most of these are no-brainers...I'm still a total Ada newbie and I
haven't really got a grasp of the way things work yet...

TIA!

Francis Crick

<tmoran@acm.org> wrote in message
news:j_jb7.33402$Kd7.20784576@news1.rdc1.sfba.home.com...
>   I'd suggest Ada.Streams.Stream_IO
>
> > read a chunk of any size from any part of a file and write it into
memory
> > and pass back the pointer.
>     procedure Read (File : in     File_Type;
>                     Item :    out Stream_Element_Array;
>                     Last :    out Stream_Element_Offset;
>                     From : in     Positive_Count);
>
> > write a chunk of any size into any part of any file.
>   assuming "any file" does not include, for instance, printer output,
>     procedure Write(File : in     File_Type;
>                     Item : in     Stream_Element_Array;
>                     From : in     Positive_Count);