Re: Unexpected result using file:read("l")

[Oliver Kroth <oliver.kroth@...>]

Hi,

opening a text file in non-binary mode (no 'b' in mode) on Linux won't 
help you with a file that was written with CR+LF as line endings.
I use to snip off a terminating \r:

line = file:read('*l')
if not line then break end
line = line:gsub( '\\r$', '' )

Funny enough, the socket filter '*l' removes all '\r' characters, thus 
it may indeed may come unexpected that file:read('*l') does not.

If one has to read a lot of files line by line, one may consider to 
define a iterator factory lines that crates iterators that snip off the 
terminating '\r', like:

for line in lines( file ) do
 ...
end


Regards,

Oliver

Am 24.03.22 um 16:02 schrieb Francisco Olarte:
> Mitchell:
>
> On Thu, 24 Mar 2022 at 15:39, Mitchell <lists@triplequasar.com> wrote:
> > I don't have a Windows box to test this on, but if I recall correctly, opening the file in binary mode on Windows should allow 'l' to also trim '\r'. I could be misremembering though.
> It is the other way round. Opening a file in binary gives you
> uninterpreted bytes. The C runtime ( on which lua builds ) is supposed
> to translate whatever you os uses for end of line into a '\n'. So a
> file "ab\012bc\015de\015\012" is read the same in every OS in binary
> mode, but you may have problems (CP/M like CRLF, unixlike LF or
> Macintosh(classic, not osx) CR ).
> In default (text) mode they could be read differently. Also, normally
> it is not a good idea to use binary mode for text files, or viceversa.
>
> Francisco Olarte.
>
>
>
>
>
>
> > Cheers,
> > Mitchell