Re: Q: Line_IO

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

Anh Vo schrieb:

> I am curious how close when compared to GNAT.IO.Put_Line and
> GNAT.IO.Get_Line. If it is close enough, I would say it is the best of
> both worlds, speed and portability.

For reading, I don't know how to compare GNAT.IO.Get_Line.
This Get_Line seems to ignore the end of input.
AFAICS, it is implemented using C's getchar(), non-macro-versions
IIUC. Never compares the result of imported get_char <- getchar()
against C's EOF.

GNAT.IO.Put_Line seem to be slow.
It, too, ends up calling C's putchar().
In fact, it appears to be running many times more slowly than
Text_IO.Put_Line.

A few statistical results, sampled on one GNU/Linux machine.

$ gnatmake -g -O2 -gnatwa -gnatn test_line_io.adb

$ ./test_line_io < {250MB text file} > {some output file}


With Line_IO.Print and

-  Line_IO.Getline: ~3 seconds.
-  Text_IO.Get_Line: ~7.5 seconds.

With Ada.Text_IO.Put_Line and

-  Line_IO.Getline: ~21 seconds
-  Text_IO.Get_Line: ~27 seconds