OpenEuphoria

Irv: Re: For loop and a newbie

• Posted by Michael Sabal <mikes at notations.com> Mar 26, 2001
• 428 views

I've been doing this like this quite a bit lately.  You're looking for a =
chr() routine, but in Euphoria, we don't need one.  The asc() routine is a =
little more difficult, but Irv's example with value() will fill in nicely.

For the moment, we'll assume your device is connected to LPT1: in a DOS =
environment.  All file pointers are atoms, so we'd open it for writing =
using 2 lines of code, and a little error-checking:

atom fp
fp =3D open ("lpt1:","wb")  -- If we're sending control codes,=20
             -- it's better to us binary.
if fp =3D -1 then abort(1) end if -- a file pointer of -1 indicates an =
error.

I'm going to use HP PCL5 control codes to demonstrate printing a 10x10 =
black box at coordinate (100,100) on the paper:

puts(fp,27&"*p100x100Y"&27&"*c10a10b0P")

The ampersand (&) in Euphoria is for concatenation.  Since every
ASCII character is simply a number from 0 to 255, and a string is just an =
array (i.e., sequence) of numbers; we just have to concatenate the =
non-readable numbers to the string of readable numbers.  I could have done =
the same line a little lengthier using an intermediate sequence:

constant RAWDATA =3D {27,"*p100x100Y",27,"*c10a10b0P"}
  -- I'm using a constant for demo, but this could just as easily come
  -- from the command line or a data file.
sequence printstring
printstring =3D "" -- No variable is pre-initialized in Euphoria.

for ctr =3D 1 to length(RAWDATA) do -- except for-loop variables.
  printstring &=3D RAWDATA[ctr]
end for
puts(fp,printstring) -- I assume fp has been opened elsewhere=20
  -- in the program.

Also, don't forget to close any buffered data streams before you end your =
program.  Most spooled or queued printers won't print a single byte until =
the stream is closed:

close(fp)

Hopefully this will answer a few of your questions.
Michael J. Sabal


>>> jc at cknet.net 03/26/01 11:21AM >>>
This little routine (that I'd written years ago in pascal) is to send =
control codes to printers or cash drawers.