gen/dc_help.txt

/*
 * *****************************************************************************
 *
 * Copyright 2018 Gavin D. Howard
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 *
 * *****************************************************************************
 *
 * The dc help text.
 *
 */

usage: %s [options] [file...]

dc is a reverse-polish notation command-line calculator which supports unlimited
precision arithmetic. For details, see this dc's full manual
(https://github.com/gavinhoward/bc/blob/master/manuals/dc.md).

This dc is (mostly) compatible with the FreeBSD dc and the GNU dc. See the
FreeBSD man page (https://www.unix.com/man-page/FreeBSD/1/dc/) and the GNU dc
manual (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html) for
details.

This dc has a few differences from the two above:

  1) When printing a byte stream (command "P"), this bc follows what the FreeBSD
     dc does.
  2) This dc implements the GNU extensions for divmod ("~") and modular
     exponentiation ("|").
  3) This dc implements all FreeBSD extensions, except for "J" and "M".
  4) Like the FreeBSD dc, this dc supports extended registers. However, they are
     implemented differently. When it encounters whitespace where a register
     should be, it skips the whitespace. If the character following is not
     a lowercase letter, an error is issued. Otherwise, the register name is
     parsed by the following regex:

       [a-z][a-z0-9_]*

     This generally means that register names will be surrounded by whitespace.

     Examples:

       l idx s temp L index S temp2 < do_thing

     Also note that, unlike the FreeBSD dc, extended registers are not even
     parsed unless the "-x" option is given. Instead, the space after a command
     that requires a register name is taken as the register name.

Options:

  -e  expr  --expression=expr

      Run "expr" and quit. If multiple expressions or files (see below) are
      given, they are all run. After running, dc will exit.

  -f  file  --file=file

      Run the dc code in "file" and exit. See above.

  -h  --help

      Print this usage message and exit.

  -V  --version

      Print version and copyright and exit.

  -x  --extended-register

      Enable extended register mode.