Re: libapl stdout

[Dr . Jürgen Sauermann]

Hi,

two explanations:

1. ⎕FIO does not allow closing of file descriptors 0, 1, and 2 aka. 
stdin, stdout and stderr.
Closing them is usually a mistake because it disconnects the interpreter 
from its I/O. That
should explain the DOMAIN ERRORs.

2. Files opened with fopen (aka.*⎕FIO[3]*) are buffered. If they refer 
to stdout or stderr
then you will probably see the output only after a newline character (which
*rs←(⍕⍳4) *is lacking). The characters not vet written are written on 
*fclose()*
but that is certainly not the proper way of enforcing their printout..

Best Regards,
Jürgen


On 2/2/23 10:14 PM, enztec@gmx.com wrote:
> Hi Jürgen
>
> this is what i'm testing and i must be missing something -
>
> //apl_exec('h ← "w" ⎕fio[3] "https.tmp"'); // h → 3     good '1 2 3 4' written 
> to file
> //apl_exec('h ← "w" ⎕fio[3] "/dev/stdin"'); // h → 3   '1 2 3 4' written to 
> screen
> apl_exec('h ← "w" ⎕fio[3] "/dev/stdout"'); // h → 3   '1 2 3 4' written to 
> screen
> //apl_exec('h ← "w" ⎕fio[3] "/dev/tty"'); // h → 3  '1 2 3 4' written to screen
> //apl_exec('h ← "w" ⎕fio[3] "/dev/stderr"'); // h → 3  '1 2 3 4' written to 
> screen
> //apl_exec('h←0'); // causes domain error
> //apl_exec('h←1'); // causes domain error
> //apl_exec('h←2'); // causes domain error
> //apl_exec('h←3'); // causes domain error
> apl_exec('"h :", h');
> writeln('1');
> apl_exec('rs←(⍕⍳4) ⎕fio[23] h');
> writeln('2');
> apl_exec('rs←⎕fio[4] h'); // closing causes display on screeb  (but not to 
> stdout?)