Re: End_Of_File does not work as expected...

[Jeff Carter <jrcarter@acm.org>]

Mats Weber wrote:
> 
> I find Jeff Carter's reply overly pedantic and paternalistic, given the
> reasonable question being asked. And students are welcome to this newsgroup.

I was trying to allow the questioner to figure the answer out himself.
In my experience, information is more likely to be retained when figured
out than when given.

> If you want to write the equivalent of UNIX's echo using Text_IO, you
> must follow the complete file structure including lines and pages:

The UNIX echo command echoes its command line arguments, IIRC. The
questioner does not appear to be writing an equivalent program. I am not
sure what he is trying to accomplish.

> 
> while not End_Of_File loop
>    while not End_Of_Page loop
>       while not End_Of_Line loop
>          Get(c);
>          Put(c);
>       end loop;
>       Skip_Line;   -- can be omitted.
>       New_Line;
>    end loop;
>    Skip_Page;   -- can be omitted.
>    New_Page;
> end loop;

If the code does not skip line terminators, then it will raise
End_Error. If the file does not contain page terminators, this code will
raise End_Error. When reading from the keyboard, End_Of_File is usually
always False.

My advice would be to use a Get_Line function and Put_Line, and have a
handler for End_Error.

-- 
Jeff Carter
"Nobody expects the Spanish Inquisition!"
Monty Python's Flying Circus