Actually... thinking about this a bit more, there were some error
cases where I wouldn't properly cleanup after. Here's a better
approach:
cfgets=:3 :0
y=. {.y,999 NB. max line length
r=. ''
libc=. (' ',~unxlib'c') 2 :'(m,n)&cd'
err=. [:echo],' error: ',1{::cderx bind''
fd=. 'dup >i i'libc 0
if.0>fd do.err 'dup'
else.
f=. {.'fdopen * i *c'libc fd;,'r'
if.0=f do.err'fdopen'if.'close >i i'libc<fd do.err'close'end.
else.
buf=. mema y
if.0=buf do.echo'mema error'
else.
if.0='fgets *c *c i *' libc (<buf);y;<f do.err'fgets'
else.
r=. ({.~ i.&LF)memr buf,0,y
if.memf buf do.echo'memf error'
end.
end.
end.
if.'fclose >i *'libc <f do.err'fclose'
if.'close >i i'libc<fd do.err'close'end.
end.
end.
end.
r
)
Doesn't exactly roll off the tongue, but should be relatively robust
in contexts where J's stdin is a reasonable place to collect text
from.
Thanks,
--
Raul
On Thu, Jun 21, 2018 at 8:40 PM Raul Miller <[email protected]> wrote:
>
> And here's a version of Xiao-Yong Jin's implementation that cleans up
> after itself (and checks for errors (though that might be overkill):
>
> cfgets=:3 :0
> y=. {.y,999 NB. max line length
> libc=. (' ',~unxlib'c') 2 :'(m,n)&cd'
> fd=. 'dup >i i'libc 0
> if. 0>fd do.
> echo 'dup error: ',1{::cderx''
> else.
> f=. {. 'fdopen * i *c'libc fd;,'r'
> if. 0=f do.
> echo 'fdopen error: ',1{::cderx''
> else.
> buf=. mema y
> if. 0=buf do.
> echo 'mema error'
> else.
> if. 0='fgets *c *c i *' libc (<buf);y;<f do.
> echo 'fgets error: ',1{::cderx''
> else.
> r=. ({.~ i.&LF)memr buf,0,y
> if. memf buf do.
> echo 'memf error'
> else.
> if. 'fclose >i *'libc <f do.
> echo 'fclose error: ',1{::cderx''
> if. 'close >i i'libc <fd do.
> echo 'close error: ',1{::cderx''
> end.
> end.
> end.
> r
> end.
> end.
> end.
> end.
> )
>
> Only good for jconsole, but might be useful there.
>
> Also, I've not tested this under windows. It might ({.~ <./@i.&CRLF)
> on the r=. line, or maybe something more than that for windows.
>
> Thanks,
>
> --
> RaulOn Thu, Jun 21, 2018 at 11:16 AM Raul Miller <[email protected]>
> wrote:
> >
> > Ah, never mind - this works fine in jconsole:
> >
> > l=.({.~i.&LF)memr b,0,s[(c,' fgets *c *c i *')cd(<b=.mema
> > s);(s=.256);<f=.{.(c,' fdopen * i *c')cd(d=.0 cd~' dup > i
> > i',~c=.unxlib'c');1 1$'r'
> >
> > (Though repeated use should split that between setup and the actual
> > line read, and of course, you would want a larger value for s if you
> > wanted to read longer lines.)
> >
> > Thanks,
> >
> > --
> > Raul
> >
> > On Thu, Jun 21, 2018 at 11:02 AM Raul Miller <[email protected]> wrote:
> > >
> > > Oddly, that doesn't work on my machine.
> > >
> > > It looks plausible, though.
> > >
> > > Thanks,
> > >
> > > --
> > > Raul
> > > On Thu, Jun 21, 2018 at 3:09 AM Xiao-Yong Jin <[email protected]> wrote:
> > > >
> > > > You can also call c library functions.
> > > >
> > > > l=.({.~i.&LF)memr b,0,s[(c,' fgets *c *c i *')cd(<b=.mema
> > > > s);(s=.256);<f=.{.(c,' fdopen * i *c')cd(d=.0 cd~' dup > i
> > > > i',~c=.unxlib'c');1 1$'r'
> > > > hello read line
> > > > (;$)l
> > > > ┌───────────────┬──┐
> > > > │hello read line│15│
> > > > └───────────────┴──┘
> > > > (c,' fclose i *')cd<f
> > > >
> > > >
> > > > > On Jun 19, 2018, at 8:13 PM, Raul Miller <[email protected]>
> > > > > wrote:
> > > > >
> > > > > Actually, thinking about this - 1!:1 reads the whole file, so it's
> > > > > stty won't make a difference .- you'd need to use control-D to
> > > > > terminate everything you send to it interactively.
> > > > >
> > > > > One approach - not incredibly efficient, but interactive
> > > > > line-at-a-time input isn't about efficiency, might be:
> > > > >
> > > > > LINE=: 2!:0'read line; echo "$line"'
> > > > >
> > > > > This relies on 2!:0 being handled by /bin/sh (and note that you'll get
> > > > > a trailing LF character when you do this). The double quotes are so
> > > > > that redundant whitespace isn't removed by the shell...
> > > > >
> > > > > Or, if you want that as a verb:
> > > > >
> > > > > readline=: 2!:0 bind 'read line; echo "$line"'
> > > > >
> > > > > I hope this helps.
> > > > >
> > > > > --
> > > > > Raul
> > > > > On Tue, Jun 19, 2018 at 8:57 PM Raul Miller <[email protected]>
> > > > > wrote:
> > > > >>
> > > > >> Ah.. experimenting with this:
> > > > >>
> > > > >> stdin'' reads till end of file (hit control-D to finish input)
> > > > >> readln'' as defined in this thread returns immediately, reading an
> > > > >> empty string.
> > > > >>
> > > > >> At least on *my* system.
> > > > >>
> > > > >> I tried running
> > > > >>
> > > > >> stty eol ^J before starting J, thinking that would fix it, but it did
> > > > >> not. But I'm running OSX where it might be that there's some "new and
> > > > >> improved" mechanism for defining the end of line character.
> > > > >>
> > > > >> Anyways, this is likely an OS issue and the solution probably will
> > > > >> depend on your OS.
> > > > >>
> > > > >> I hope this helps,
> > > > >>
> > > > >> --
> > > > >> Raul
> > > > >>
> > > > >> On Tue, Jun 19, 2018 at 8:41 PM Eric Iverson
> > > > >> <[email protected]> wrote:
> > > > >>>
> > > > >>> I think the replies here miss an important part of the question.
> > > > >>> The #!
> > > > >>> script.
> > > > >>>
> > > > >>> #! /usr/bin/j8
> > > > >>> stdin''
> > > > >>>
> > > > >>> On Tue, Jun 19, 2018 at 8:21 PM, Don Guinn <[email protected]>
> > > > >>> wrote:
> > > > >>>
> > > > >>>> It appears that the right argument is ignored. Perhaps have it be
> > > > >>>> displayed
> > > > >>>> on the same line as the input.
> > > > >>>>
> > > > >>>> readln 'Name: '
> > > > >>>>
> > > > >>>> On Tue, Jun 19, 2018 at 6:18 PM Raul Miller
> > > > >>>> <[email protected]> wrote:
> > > > >>>>
> > > > >>>>> 1 -:&(3!:3) 01
> > > > >>>>> 1
> > > > >>>>>
> > > > >>>>> No difference in what's represented, so the only difference is in
> > > > >>>>> how
> > > > >>>>> you type it / the leading zero / ...
> > > > >>>>>
> > > > >>>>> Thanks,
> > > > >>>>>
> > > > >>>>> --
> > > > >>>>> Raul
> > > > >>>>>
> > > > >>>>> On Tue, Jun 19, 2018 at 8:15 PM Devon McCormick
> > > > >>>>> <[email protected]>
> > > > >>>>> wrote:
> > > > >>>>>>
> > > > >>>>>> How does "01" differ from "1" in this context?
> > > > >>>>>>
> > > > >>>>>> "readln" works for me within a session but I think James wants
> > > > >>>>>> to do
> > > > >>>>>> something like pipe input into a J script. This is not
> > > > >>>>>> something I've
> > > > >>>>> done
> > > > >>>>>> but it would be interesting if we can do it.
> > > > >>>>>>
> > > > >>>>>> On Tue, Jun 19, 2018 at 5:10 PM, Henry Rich
> > > > >>>>>> <[email protected]>
> > > > >>>>> wrote:
> > > > >>>>>>
> > > > >>>>>>> ? The 01 is correct as it stands. On Windows I get correct
> > > > >>>> operation:
> > > > >>>>>>>
> > > > >>>>>>> readln =: [: (1!:01) 1:
> > > > >>>>>>> readln''
> > > > >>>>>>> abcdefg
> > > > >>>>>>> abcdefg
> > > > >>>>>>>
> > > > >>>>>>> The first line is what I typed, the second is the JE's result
> > > > >>>>>>>
> > > > >>>>>>> Henry Rich
> > > > >>>>>>>
> > > > >>>>>>>
> > > > >>>>>>> On 6/19/2018 5:05 PM, james faure wrote:
> > > > >>>>>>>
> > > > >>>>>>>> Either way, it's no good
> > > > >>>>>>>>
> > > > >>>>>>>> ________________________________
> > > > >>>>>>>> From: Programming <[email protected]> on
> > > > >>>>> behalf
> > > > >>>>>>>> of devonmcc <[email protected]>
> > > > >>>>>>>> Sent: Tuesday, June 19, 2018 11:00:39 PM
> > > > >>>>>>>> To: [email protected]
> > > > >>>>>>>> Subject: Re: [Jprogramming] getline
> > > > >>>>>>>>
> > > > >>>>>>>> The "01" following the "!:" is probably supposed to be "0]1".
> > > > >>>>>>>>
> > > > >>>>>>>>
> > > > >>>>>>>> Sent from my Verizon, Samsung Galaxy smartphone
> > > > >>>>>>>> -------- Original message --------From: Michal Wallace <
> > > > >>>>>>>> [email protected]> Date: 6/19/18 16:06 (GMT-05:00) To:
> > > > >>>>>>>> [email protected] Subject: Re: [Jprogramming] getline
> > > > >>>>>>>> readln =: [: (1!:01) 1:
> > > > >>>>>>>>
> > > > >>>>>>>>
> > > > >>>>>>>>
> > > > >>>>>>>>
> > > > >>>>>>>> On Tue, Jun 19, 2018 at 2:45 PM james faure
> > > > >>>>>>>> <[email protected]
> > > > >>>>>
> > > > >>>>>>>> wrote:
> > > > >>>>>>>>
> > > > >>>>>>>> Hello, how can one read stdin one line at a time ?
> > > > >>>>>>>>>
> > > > >>>>>>>>>
> > > > >>>>>>>>> #! /usr/bin/j8
> > > > >>>>>>>>>
> > > > >>>>>>>>> stdin''
> > > > >>>>>>>>>
> > > > >>>>>>>>>
> > > > >>>>>>>>> is no good.
> > > > >>>>>>>>>
> > > > >>>>> ----------------------------------------------------------------------
> > > > >>>>>>>>> For information about J forums see
> > > > >>>>> http://www.jsoftware.com/forums.htm
> > > > >>>>>>>>>
> > > > >>>>>>>> ------------------------------------------------------------
> > > > >>>> ----------
> > > > >>>>>>>> For information about J forums see
> > > > >>>>> http://www.jsoftware.com/forums.htm
> > > > >>>>>>>> ------------------------------------------------------------
> > > > >>>> ----------
> > > > >>>>>>>> For information about J forums see
> > > > >>>>> http://www.jsoftware.com/forums.htm
> > > > >>>>>>>> ------------------------------------------------------------
> > > > >>>> ----------
> > > > >>>>>>>> For information about J forums see
> > > > >>>>> http://www.jsoftware.com/forums.htm
> > > > >>>>>>>>
> > > > >>>>>>>
> > > > >>>>>>>
> > > > >>>>>>> ---
> > > > >>>>>>> This email has been checked for viruses by AVG.
> > > > >>>>>>> https://www.avg.com
> > > > >>>>>>>
> > > > >>>>>>>
> > > > >>>>>>> ------------------------------------------------------------
> > > > >>>> ----------
> > > > >>>>>>> For information about J forums see http://www.jsoftware.com/
> > > > >>>> forums.htm
> > > > >>>>>>>
> > > > >>>>>>
> > > > >>>>>>
> > > > >>>>>>
> > > > >>>>>> --
> > > > >>>>>>
> > > > >>>>>> Devon McCormick, CFA
> > > > >>>>>>
> > > > >>>>>> Quantitative Consultant
> > > > >>>>>> ----------------------------------------------------------------------
> > > > >>>>>> For information about J forums see
> > > > >>>>>> http://www.jsoftware.com/forums.htm
> > > > >>>>> ----------------------------------------------------------------------
> > > > >>>>> For information about J forums see
> > > > >>>>> http://www.jsoftware.com/forums.htm
> > > > >>>> ----------------------------------------------------------------------
> > > > >>>> For information about J forums see
> > > > >>>> http://www.jsoftware.com/forums.htm
> > > > >>>>
> > > > >>> ----------------------------------------------------------------------
> > > > >>> For information about J forums see
> > > > >>> http://www.jsoftware.com/forums.htm
> > > > > ----------------------------------------------------------------------
> > > > > For information about J forums see http://www.jsoftware.com/forums.htm
> > > >
> > > > ----------------------------------------------------------------------
> > > > For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
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