5d934bc0c5
This version omits the printing of a copyright header in interactive mode and the dc command now exits after execution of the commands passed via -e or -f instead of switching to interactive mode. To pass further commands via STDIN when dc has been invoked with -e or -f, add "-f -" to the parameter list.
1200 lines
38 KiB
Groff
1200 lines
38 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2018-2020 Gavin D. Howard and contributors.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions are met:
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.\"
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.\" * Redistributions of source code must retain the above copyright notice,
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.\" this list of conditions and the following disclaimer.
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.\"
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.\" * Redistributions in binary form must reproduce the above copyright notice,
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.\" this list of conditions and the following disclaimer in the documentation
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.\" and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.TH "DC" "1" "July 2020" "Gavin D. Howard" "General Commands Manual"
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.SH Name
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.PP
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dc \- arbitrary\-precision reverse\-Polish notation calculator
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.SH SYNOPSIS
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.PP
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\f[B]dc\f[] [\f[B]\-hiPvVx\f[]] [\f[B]\-\-version\f[]]
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[\f[B]\-\-help\f[]] [\f[B]\-\-interactive\f[]] [\f[B]\-\-no\-prompt\f[]]
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[\f[B]\-\-extended\-register\f[]] [\f[B]\-e\f[] \f[I]expr\f[]]
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[\f[B]\-\-expression\f[]=\f[I]expr\f[]...] [\f[B]\-f\f[]
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\f[I]file\f[]...] [\f[B]\-file\f[]=\f[I]file\f[]...] [\f[I]file\f[]...]
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.SH DESCRIPTION
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.PP
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dc(1) is an arbitrary\-precision calculator.
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It uses a stack (reverse Polish notation) to store numbers and results
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of computations.
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Arithmetic operations pop arguments off of the stack and push the
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results.
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.PP
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If no files are given on the command\-line as extra arguments (i.e., not
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as \f[B]\-f\f[] or \f[B]\-\-file\f[] arguments), then dc(1) reads from
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\f[B]stdin\f[].
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Otherwise, those files are processed, and dc(1) will then exit.
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.PP
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This is different from the dc(1) on OpenBSD and possibly other dc(1)
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implementations, where \f[B]\-e\f[] (\f[B]\-\-expression\f[]) and
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\f[B]\-f\f[] (\f[B]\-\-file\f[]) arguments cause dc(1) to execute them
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and exit.
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The reason for this is that this dc(1) allows users to set arguments in
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the environment variable \f[B]DC_ENV_ARGS\f[] (see the \f[B]ENVIRONMENT
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VARIABLES\f[] section).
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Any expressions given on the command\-line should be used to set up a
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standard environment.
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For example, if a user wants the \f[B]scale\f[] always set to
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\f[B]10\f[], they can set \f[B]DC_ENV_ARGS\f[] to \f[B]\-e 10k\f[], and
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this dc(1) will always start with a \f[B]scale\f[] of \f[B]10\f[].
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.PP
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If users want to have dc(1) exit after processing all input from
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\f[B]\-e\f[] and \f[B]\-f\f[] arguments (and their equivalents), then
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they can just simply add \f[B]\-e q\f[] as the last command\-line
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argument or define the environment variable \f[B]DC_EXPR_EXIT\f[].
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.SH OPTIONS
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.PP
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The following are the options that dc(1) accepts.
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.TP
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.B \f[B]\-h\f[], \f[B]\-\-help\f[]
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Prints a usage message and quits.
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.RS
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.RE
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.TP
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.B \f[B]\-v\f[], \f[B]\-V\f[], \f[B]\-\-version\f[]
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Print the version information (copyright header) and exit.
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.RS
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.RE
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.TP
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.B \f[B]\-i\f[], \f[B]\-\-interactive\f[]
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Forces interactive mode.
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(See the \f[B]INTERACTIVE MODE\f[] section.)
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]\-P\f[], \f[B]\-\-no\-prompt\f[]
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Disables the prompt in TTY mode.
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(The prompt is only enabled in TTY mode.
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See the \f[B]TTY MODE\f[] section) This is mostly for those users that
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do not want a prompt or are not used to having them in dc(1).
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Most of those users would want to put this option in
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\f[B]DC_ENV_ARGS\f[].
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]\-x\f[] \f[B]\-\-extended\-register\f[]
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Enables extended register mode.
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See the \f[I]Extended Register Mode\f[] subsection of the
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\f[B]REGISTERS\f[] section for more information.
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]\-e\f[] \f[I]expr\f[], \f[B]\-\-expression\f[]=\f[I]expr\f[]
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Evaluates \f[I]expr\f[].
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If multiple expressions are given, they are evaluated in order.
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If files are given as well (see below), the expressions and files are
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evaluated in the order given.
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This means that if a file is given before an expression, the file is
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read in and evaluated first.
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.RS
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.PP
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After processing all expressions and files, dc(1) will exit, unless
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\f[B]\-\f[] (\f[B]stdin\f[]) was given as an argument at least once to
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\f[B]\-f\f[] or \f[B]\-\-file\f[].
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]\-f\f[] \f[I]file\f[], \f[B]\-\-file\f[]=\f[I]file\f[]
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Reads in \f[I]file\f[] and evaluates it, line by line, as though it were
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read through \f[B]stdin\f[].
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If expressions are also given (see above), the expressions are evaluated
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in the order given.
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.RS
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.PP
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After processing all expressions and files, dc(1) will exit, unless
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\f[B]\-\f[] (\f[B]stdin\f[]) was given as an argument at least once to
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\f[B]\-f\f[] or \f[B]\-\-file\f[].
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However, if any other \f[B]\-e\f[], \f[B]\-\-expression\f[],
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\f[B]\-f\f[], or \f[B]\-\-file\f[] arguments are given after that, bc(1)
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will give a fatal error and exit.
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.PP
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All long options are \f[B]non\-portable extensions\f[].
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.SH STDOUT
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.PP
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Any non\-error output is written to \f[B]stdout\f[].
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.PP
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\f[B]Note\f[]: Unlike other dc(1) implementations, this dc(1) will issue
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a fatal error (see the \f[B]EXIT STATUS\f[] section) if it cannot write
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to \f[B]stdout\f[], so if \f[B]stdout\f[] is closed, as in \f[B]dc
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>&\-\f[], it will quit with an error.
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This is done so that dc(1) can report problems when \f[B]stdout\f[] is
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redirected to a file.
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.PP
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If there are scripts that depend on the behavior of other dc(1)
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implementations, it is recommended that those scripts be changed to
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redirect \f[B]stdout\f[] to \f[B]/dev/null\f[].
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.SH STDERR
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.PP
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Any error output is written to \f[B]stderr\f[].
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.PP
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\f[B]Note\f[]: Unlike other dc(1) implementations, this dc(1) will issue
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a fatal error (see the \f[B]EXIT STATUS\f[] section) if it cannot write
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to \f[B]stderr\f[], so if \f[B]stderr\f[] is closed, as in \f[B]dc
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2>&\-\f[], it will quit with an error.
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This is done so that dc(1) can exit with an error code when
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\f[B]stderr\f[] is redirected to a file.
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.PP
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If there are scripts that depend on the behavior of other dc(1)
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implementations, it is recommended that those scripts be changed to
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redirect \f[B]stderr\f[] to \f[B]/dev/null\f[].
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.SH SYNTAX
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.PP
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Each item in the input source code, either a number (see the
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\f[B]NUMBERS\f[] section) or a command (see the \f[B]COMMANDS\f[]
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section), is processed and executed, in order.
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Input is processed immediately when entered.
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.PP
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\f[B]ibase\f[] is a register (see the \f[B]REGISTERS\f[] section) that
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determines how to interpret constant numbers.
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It is the "input" base, or the number base used for interpreting input
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numbers.
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\f[B]ibase\f[] is initially \f[B]10\f[].
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The max allowable value for \f[B]ibase\f[] is \f[B]16\f[].
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The min allowable value for \f[B]ibase\f[] is \f[B]2\f[].
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The max allowable value for \f[B]ibase\f[] can be queried in dc(1)
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programs with the \f[B]T\f[] command.
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.PP
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\f[B]obase\f[] is a register (see the \f[B]REGISTERS\f[] section) that
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determines how to output results.
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It is the "output" base, or the number base used for outputting numbers.
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\f[B]obase\f[] is initially \f[B]10\f[].
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The max allowable value for \f[B]obase\f[] is \f[B]DC_BASE_MAX\f[] and
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can be queried with the \f[B]U\f[] command.
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The min allowable value for \f[B]obase\f[] is \f[B]2\f[].
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Values are output in the specified base.
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.PP
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The \f[I]scale\f[] of an expression is the number of digits in the
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result of the expression right of the decimal point, and \f[B]scale\f[]
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is a register (see the \f[B]REGISTERS\f[] section) that sets the
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precision of any operations (with exceptions).
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\f[B]scale\f[] is initially \f[B]0\f[].
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\f[B]scale\f[] cannot be negative.
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The max allowable value for \f[B]scale\f[] can be queried in dc(1)
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programs with the \f[B]V\f[] command.
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.SS Comments
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.PP
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Comments go from \f[B]#\f[] until, and not including, the next newline.
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This is a \f[B]non\-portable extension\f[].
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.SH NUMBERS
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.PP
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Numbers are strings made up of digits, uppercase letters up to
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\f[B]F\f[], and at most \f[B]1\f[] period for a radix.
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Numbers can have up to \f[B]DC_NUM_MAX\f[] digits.
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Uppercase letters are equal to \f[B]9\f[] + their position in the
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alphabet (i.e., \f[B]A\f[] equals \f[B]10\f[], or \f[B]9+1\f[]).
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If a digit or letter makes no sense with the current value of
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\f[B]ibase\f[], they are set to the value of the highest valid digit in
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\f[B]ibase\f[].
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.PP
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Single\-character numbers (i.e., \f[B]A\f[] alone) take the value that
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they would have if they were valid digits, regardless of the value of
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\f[B]ibase\f[].
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This means that \f[B]A\f[] alone always equals decimal \f[B]10\f[] and
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\f[B]F\f[] alone always equals decimal \f[B]15\f[].
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.SH COMMANDS
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.PP
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The valid commands are listed below.
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.SS Printing
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.PP
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These commands are used for printing.
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.TP
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.B \f[B]p\f[]
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Prints the value on top of the stack, whether number or string, and
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prints a newline after.
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.RS
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.PP
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This does not alter the stack.
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.RE
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.TP
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.B \f[B]n\f[]
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Prints the value on top of the stack, whether number or string, and pops
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it off of the stack.
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.RS
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.RE
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.TP
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.B \f[B]P\f[]
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Pops a value off the stack.
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.RS
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.PP
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If the value is a number, it is truncated and the absolute value of the
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result is printed as though \f[B]obase\f[] is \f[B]UCHAR_MAX+1\f[] and
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each digit is interpreted as an ASCII character, making it a byte
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stream.
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.PP
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If the value is a string, it is printed without a trailing newline.
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]f\f[]
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Prints the entire contents of the stack, in order from newest to oldest,
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without altering anything.
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.RS
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.PP
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Users should use this command when they get lost.
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.RE
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.SS Arithmetic
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.PP
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These are the commands used for arithmetic.
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.TP
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.B \f[B]+\f[]
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The top two values are popped off the stack, added, and the result is
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pushed onto the stack.
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The \f[I]scale\f[] of the result is equal to the max \f[I]scale\f[] of
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both operands.
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.RS
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.RE
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.TP
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.B \f[B]\-\f[]
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The top two values are popped off the stack, subtracted, and the result
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is pushed onto the stack.
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The \f[I]scale\f[] of the result is equal to the max \f[I]scale\f[] of
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both operands.
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.RS
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.RE
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.TP
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.B \f[B]*\f[]
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The top two values are popped off the stack, multiplied, and the result
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is pushed onto the stack.
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If \f[B]a\f[] is the \f[I]scale\f[] of the first expression and
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\f[B]b\f[] is the \f[I]scale\f[] of the second expression, the
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\f[I]scale\f[] of the result is equal to
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\f[B]min(a+b,max(scale,a,b))\f[] where \f[B]min()\f[] and \f[B]max()\f[]
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return the obvious values.
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.RS
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.RE
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.TP
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.B \f[B]/\f[]
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The top two values are popped off the stack, divided, and the result is
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pushed onto the stack.
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The \f[I]scale\f[] of the result is equal to \f[B]scale\f[].
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.RS
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.PP
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The first value popped off of the stack must be non\-zero.
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.RE
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.TP
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.B \f[B]%\f[]
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The top two values are popped off the stack, remaindered, and the result
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is pushed onto the stack.
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.RS
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.PP
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Remaindering is equivalent to 1) Computing \f[B]a/b\f[] to current
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\f[B]scale\f[], and 2) Using the result of step 1 to calculate
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\f[B]a\-(a/b)*b\f[] to \f[I]scale\f[]
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\f[B]max(scale+scale(b),scale(a))\f[].
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.PP
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The first value popped off of the stack must be non\-zero.
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.RE
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.TP
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.B \f[B]~\f[]
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The top two values are popped off the stack, divided and remaindered,
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and the results (divided first, remainder second) are pushed onto the
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stack.
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This is equivalent to \f[B]x y / x y %\f[] except that \f[B]x\f[] and
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\f[B]y\f[] are only evaluated once.
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.RS
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.PP
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The first value popped off of the stack must be non\-zero.
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]^\f[]
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The top two values are popped off the stack, the second is raised to the
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power of the first, and the result is pushed onto the stack.
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.RS
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.PP
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The first value popped off of the stack must be an integer, and if that
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value is negative, the second value popped off of the stack must be
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non\-zero.
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.RE
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.TP
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.B \f[B]v\f[]
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The top value is popped off the stack, its square root is computed, and
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the result is pushed onto the stack.
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The \f[I]scale\f[] of the result is equal to \f[B]scale\f[].
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.RS
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.PP
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The value popped off of the stack must be non\-negative.
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.RE
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.TP
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.B \f[B]_\f[]
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If this command \f[I]immediately\f[] precedes a number (i.e., no spaces
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or other commands), then that number is input as a negative number.
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.RS
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.PP
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Otherwise, the top value on the stack is popped and copied, and the copy
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is negated and pushed onto the stack.
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This behavior without a number is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]b\f[]
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The top value is popped off the stack, and if it is zero, it is pushed
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back onto the stack.
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Otherwise, its absolute value is pushed onto the stack.
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]|\f[]
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The top three values are popped off the stack, a modular exponentiation
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is computed, and the result is pushed onto the stack.
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.RS
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.PP
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The first value popped is used as the reduction modulus and must be an
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integer and non\-zero.
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The second value popped is used as the exponent and must be an integer
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and non\-negative.
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The third value popped is the base and must be an integer.
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]G\f[]
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The top two values are popped off of the stack, they are compared, and a
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\f[B]1\f[] is pushed if they are equal, or \f[B]0\f[] otherwise.
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B]N\f[]
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The top value is popped off of the stack, and if it a \f[B]0\f[], a
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\f[B]1\f[] is pushed; otherwise, a \f[B]0\f[] is pushed.
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
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.B \f[B](\f[]
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The top two values are popped off of the stack, they are compared, and a
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\f[B]1\f[] is pushed if the first is less than the second, or \f[B]0\f[]
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otherwise.
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.RS
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.PP
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This is a \f[B]non\-portable extension\f[].
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.RE
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.TP
|
|
.B \f[B]{\f[]
|
|
The top two values are popped off of the stack, they are compared, and a
|
|
\f[B]1\f[] is pushed if the first is less than or equal to the second,
|
|
or \f[B]0\f[] otherwise.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B])\f[]
|
|
The top two values are popped off of the stack, they are compared, and a
|
|
\f[B]1\f[] is pushed if the first is greater than the second, or
|
|
\f[B]0\f[] otherwise.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]}\f[]
|
|
The top two values are popped off of the stack, they are compared, and a
|
|
\f[B]1\f[] is pushed if the first is greater than or equal to the
|
|
second, or \f[B]0\f[] otherwise.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]M\f[]
|
|
The top two values are popped off of the stack.
|
|
If they are both non\-zero, a \f[B]1\f[] is pushed onto the stack.
|
|
If either of them is zero, or both of them are, then a \f[B]0\f[] is
|
|
pushed onto the stack.
|
|
.RS
|
|
.PP
|
|
This is like the \f[B]&&\f[] operator in bc(1), and it is \f[I]not\f[] a
|
|
short\-circuit operator.
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]m\f[]
|
|
The top two values are popped off of the stack.
|
|
If at least one of them is non\-zero, a \f[B]1\f[] is pushed onto the
|
|
stack.
|
|
If both of them are zero, then a \f[B]0\f[] is pushed onto the stack.
|
|
.RS
|
|
.PP
|
|
This is like the \f[B]||\f[] operator in bc(1), and it is \f[I]not\f[] a
|
|
short\-circuit operator.
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.SS Stack Control
|
|
.PP
|
|
These commands control the stack.
|
|
.TP
|
|
.B \f[B]c\f[]
|
|
Removes all items from ("clears") the stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]d\f[]
|
|
Copies the item on top of the stack ("duplicates") and pushes the copy
|
|
onto the stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]r\f[]
|
|
Swaps ("reverses") the two top items on the stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]R\f[]
|
|
Pops ("removes") the top value from the stack.
|
|
.RS
|
|
.RE
|
|
.SS Register Control
|
|
.PP
|
|
These commands control registers (see the \f[B]REGISTERS\f[] section).
|
|
.TP
|
|
.B \f[B]s\f[]\f[I]r\f[]
|
|
Pops the value off the top of the stack and stores it into register
|
|
\f[I]r\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]l\f[]\f[I]r\f[]
|
|
Copies the value in register \f[I]r\f[] and pushes it onto the stack.
|
|
This does not alter the contents of \f[I]r\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]S\f[]\f[I]r\f[]
|
|
Pops the value off the top of the (main) stack and pushes it onto the
|
|
stack of register \f[I]r\f[].
|
|
The previous value of the register becomes inaccessible.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]L\f[]\f[I]r\f[]
|
|
Pops the value off the top of the stack for register \f[I]r\f[] and push
|
|
it onto the main stack.
|
|
The previous value in the stack for register \f[I]r\f[], if any, is now
|
|
accessible via the \f[B]l\f[]\f[I]r\f[] command.
|
|
.RS
|
|
.RE
|
|
.SS Parameters
|
|
.PP
|
|
These commands control the values of \f[B]ibase\f[], \f[B]obase\f[], and
|
|
\f[B]scale\f[].
|
|
Also see the \f[B]SYNTAX\f[] section.
|
|
.TP
|
|
.B \f[B]i\f[]
|
|
Pops the value off of the top of the stack and uses it to set
|
|
\f[B]ibase\f[], which must be between \f[B]2\f[] and \f[B]16\f[],
|
|
inclusive.
|
|
.RS
|
|
.PP
|
|
If the value on top of the stack has any \f[I]scale\f[], the
|
|
\f[I]scale\f[] is ignored.
|
|
.RE
|
|
.TP
|
|
.B \f[B]o\f[]
|
|
Pops the value off of the top of the stack and uses it to set
|
|
\f[B]obase\f[], which must be between \f[B]2\f[] and
|
|
\f[B]DC_BASE_MAX\f[], inclusive (see the \f[B]LIMITS\f[] section).
|
|
.RS
|
|
.PP
|
|
If the value on top of the stack has any \f[I]scale\f[], the
|
|
\f[I]scale\f[] is ignored.
|
|
.RE
|
|
.TP
|
|
.B \f[B]k\f[]
|
|
Pops the value off of the top of the stack and uses it to set
|
|
\f[B]scale\f[], which must be non\-negative.
|
|
.RS
|
|
.PP
|
|
If the value on top of the stack has any \f[I]scale\f[], the
|
|
\f[I]scale\f[] is ignored.
|
|
.RE
|
|
.TP
|
|
.B \f[B]I\f[]
|
|
Pushes the current value of \f[B]ibase\f[] onto the main stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]O\f[]
|
|
Pushes the current value of \f[B]obase\f[] onto the main stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]K\f[]
|
|
Pushes the current value of \f[B]scale\f[] onto the main stack.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]T\f[]
|
|
Pushes the maximum allowable value of \f[B]ibase\f[] onto the main
|
|
stack.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]U\f[]
|
|
Pushes the maximum allowable value of \f[B]obase\f[] onto the main
|
|
stack.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]V\f[]
|
|
Pushes the maximum allowable value of \f[B]scale\f[] onto the main
|
|
stack.
|
|
.RS
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.SS Strings
|
|
.PP
|
|
The following commands control strings.
|
|
.PP
|
|
dc(1) can work with both numbers and strings, and registers (see the
|
|
\f[B]REGISTERS\f[] section) can hold both strings and numbers.
|
|
dc(1) always knows whether the contents of a register are a string or a
|
|
number.
|
|
.PP
|
|
While arithmetic operations have to have numbers, and will print an
|
|
error if given a string, other commands accept strings.
|
|
.PP
|
|
Strings can also be executed as macros.
|
|
For example, if the string \f[B][1pR]\f[] is executed as a macro, then
|
|
the code \f[B]1pR\f[] is executed, meaning that the \f[B]1\f[] will be
|
|
printed with a newline after and then popped from the stack.
|
|
.TP
|
|
.B \f[B][\f[]\f[I]characters\f[]\f[B]]\f[]
|
|
Makes a string containing \f[I]characters\f[] and pushes it onto the
|
|
stack.
|
|
.RS
|
|
.PP
|
|
If there are brackets (\f[B][\f[] and \f[B]]\f[]) in the string, then
|
|
they must be balanced.
|
|
Unbalanced brackets can be escaped using a backslash (\f[B]\\\f[])
|
|
character.
|
|
.PP
|
|
If there is a backslash character in the string, the character after it
|
|
(even another backslash) is put into the string verbatim, but the
|
|
(first) backslash is not.
|
|
.RE
|
|
.TP
|
|
.B \f[B]a\f[]
|
|
The value on top of the stack is popped.
|
|
.RS
|
|
.PP
|
|
If it is a number, it is truncated and its absolute value is taken.
|
|
The result mod \f[B]UCHAR_MAX+1\f[] is calculated.
|
|
If that result is \f[B]0\f[], push an empty string; otherwise, push a
|
|
one\-character string where the character is the result of the mod
|
|
interpreted as an ASCII character.
|
|
.PP
|
|
If it is a string, then a new string is made.
|
|
If the original string is empty, the new string is empty.
|
|
If it is not, then the first character of the original string is used to
|
|
create the new string as a one\-character string.
|
|
The new string is then pushed onto the stack.
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]x\f[]
|
|
Pops a value off of the top of the stack.
|
|
.RS
|
|
.PP
|
|
If it is a number, it is pushed back onto the stack.
|
|
.PP
|
|
If it is a string, it is executed as a macro.
|
|
.PP
|
|
This behavior is the norm whenever a macro is executed, whether by this
|
|
command or by the conditional execution commands below.
|
|
.RE
|
|
.TP
|
|
.B \f[B]>\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is greater than the second, then the contents of
|
|
register \f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
For example, \f[B]0 1>a\f[] will execute the contents of register
|
|
\f[B]a\f[], and \f[B]1 0>a\f[] will not.
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]>\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]!>\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is not greater than the second (less than or equal
|
|
to), then the contents of register \f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]!>\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]<\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is less than the second, then the contents of
|
|
register \f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]<\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]!<\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is not less than the second (greater than or equal
|
|
to), then the contents of register \f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]!<\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]=\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is equal to the second, then the contents of register
|
|
\f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]=\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]!=\f[]\f[I]r\f[]
|
|
Pops two values off of the stack that must be numbers and compares them.
|
|
If the first value is not equal to the second, then the contents of
|
|
register \f[I]r\f[] are executed.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.RE
|
|
.TP
|
|
.B \f[B]!=\f[]\f[I]r\f[]\f[B]e\f[]\f[I]s\f[]
|
|
Like the above, but will execute register \f[I]s\f[] if the comparison
|
|
fails.
|
|
.RS
|
|
.PP
|
|
If either or both of the values are not numbers, dc(1) will raise an
|
|
error and reset (see the \f[B]RESET\f[] section).
|
|
.PP
|
|
This is a \f[B]non\-portable extension\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]?\f[]
|
|
Reads a line from the \f[B]stdin\f[] and executes it.
|
|
This is to allow macros to request input from users.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]q\f[]
|
|
During execution of a macro, this exits the execution of that macro and
|
|
the execution of the macro that executed it.
|
|
If there are no macros, or only one macro executing, dc(1) exits.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]Q\f[]
|
|
Pops a value from the stack which must be non\-negative and is used the
|
|
number of macro executions to pop off of the execution stack.
|
|
If the number of levels to pop is greater than the number of executing
|
|
macros, dc(1) exits.
|
|
.RS
|
|
.RE
|
|
.SS Status
|
|
.PP
|
|
These commands query status of the stack or its top value.
|
|
.TP
|
|
.B \f[B]Z\f[]
|
|
Pops a value off of the stack.
|
|
.RS
|
|
.PP
|
|
If it is a number, calculates the number of significant decimal digits
|
|
it has and pushes the result.
|
|
.PP
|
|
If it is a string, pushes the number of characters the string has.
|
|
.RE
|
|
.TP
|
|
.B \f[B]X\f[]
|
|
Pops a value off of the stack.
|
|
.RS
|
|
.PP
|
|
If it is a number, pushes the \f[I]scale\f[] of the value onto the
|
|
stack.
|
|
.PP
|
|
If it is a string, pushes \f[B]0\f[].
|
|
.RE
|
|
.TP
|
|
.B \f[B]z\f[]
|
|
Pushes the current stack depth (before execution of this command).
|
|
.RS
|
|
.RE
|
|
.SS Arrays
|
|
.PP
|
|
These commands manipulate arrays.
|
|
.TP
|
|
.B \f[B]:\f[]\f[I]r\f[]
|
|
Pops the top two values off of the stack.
|
|
The second value will be stored in the array \f[I]r\f[] (see the
|
|
\f[B]REGISTERS\f[] section), indexed by the first value.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B];\f[]\f[I]r\f[]
|
|
Pops the value on top of the stack and uses it as an index into the
|
|
array \f[I]r\f[].
|
|
The selected value is then pushed onto the stack.
|
|
.RS
|
|
.RE
|
|
.SH REGISTERS
|
|
.PP
|
|
Registers are names that can store strings, numbers, and arrays.
|
|
(Number/string registers do not interfere with array registers.)
|
|
.PP
|
|
Each register is also its own stack, so the current register value is
|
|
the top of the stack for the register.
|
|
All registers, when first referenced, have one value (\f[B]0\f[]) in
|
|
their stack.
|
|
.PP
|
|
In non\-extended register mode, a register name is just the single
|
|
character that follows any command that needs a register name.
|
|
The only exception is a newline (\f[B]\[aq]\\n\[aq]\f[]); it is a parse
|
|
error for a newline to be used as a register name.
|
|
.SS Extended Register Mode
|
|
.PP
|
|
Unlike most other dc(1) implentations, this dc(1) provides nearly
|
|
unlimited amounts of registers, if extended register mode is enabled.
|
|
.PP
|
|
If extended register mode is enabled (\f[B]\-x\f[] or
|
|
\f[B]\-\-extended\-register\f[] command\-line arguments are given), then
|
|
normal single character registers are used \f[I]unless\f[] the character
|
|
immediately following a command that needs a register name is a space
|
|
(according to \f[B]isspace()\f[]) and not a newline
|
|
(\f[B]\[aq]\\n\[aq]\f[]).
|
|
.PP
|
|
In that case, the register name is found according to the regex
|
|
\f[B][a\-z][a\-z0\-9_]*\f[] (like bc(1) identifiers), and it is a parse
|
|
error if the next non\-space characters do not match that regex.
|
|
.SH RESET
|
|
.PP
|
|
When dc(1) encounters an error or a signal that it has a non\-default
|
|
handler for, it resets.
|
|
This means that several things happen.
|
|
.PP
|
|
First, any macros that are executing are stopped and popped off the
|
|
stack.
|
|
The behavior is not unlike that of exceptions in programming languages.
|
|
Then the execution point is set so that any code waiting to execute
|
|
(after all macros returned) is skipped.
|
|
.PP
|
|
Thus, when dc(1) resets, it skips any remaining code waiting to be
|
|
executed.
|
|
Then, if it is interactive mode, and the error was not a fatal error
|
|
(see the \f[B]EXIT STATUS\f[] section), it asks for more input;
|
|
otherwise, it exits with the appropriate return code.
|
|
.SH PERFORMANCE
|
|
.PP
|
|
Most dc(1) implementations use \f[B]char\f[] types to calculate the
|
|
value of \f[B]1\f[] decimal digit at a time, but that can be slow.
|
|
This dc(1) does something different.
|
|
.PP
|
|
It uses large integers to calculate more than \f[B]1\f[] decimal digit
|
|
at a time.
|
|
If built in a environment where \f[B]DC_LONG_BIT\f[] (see the
|
|
\f[B]LIMITS\f[] section) is \f[B]64\f[], then each integer has
|
|
\f[B]9\f[] decimal digits.
|
|
If built in an environment where \f[B]DC_LONG_BIT\f[] is \f[B]32\f[]
|
|
then each integer has \f[B]4\f[] decimal digits.
|
|
This value (the number of decimal digits per large integer) is called
|
|
\f[B]DC_BASE_DIGS\f[].
|
|
.PP
|
|
In addition, this dc(1) uses an even larger integer for overflow
|
|
checking.
|
|
This integer type depends on the value of \f[B]DC_LONG_BIT\f[], but is
|
|
always at least twice as large as the integer type used to store digits.
|
|
.SH LIMITS
|
|
.PP
|
|
The following are the limits on dc(1):
|
|
.TP
|
|
.B \f[B]DC_LONG_BIT\f[]
|
|
The number of bits in the \f[B]long\f[] type in the environment where
|
|
dc(1) was built.
|
|
This determines how many decimal digits can be stored in a single large
|
|
integer (see the \f[B]PERFORMANCE\f[] section).
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_BASE_DIGS\f[]
|
|
The number of decimal digits per large integer (see the
|
|
\f[B]PERFORMANCE\f[] section).
|
|
Depends on \f[B]DC_LONG_BIT\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_BASE_POW\f[]
|
|
The max decimal number that each large integer can store (see
|
|
\f[B]DC_BASE_DIGS\f[]) plus \f[B]1\f[].
|
|
Depends on \f[B]DC_BASE_DIGS\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_OVERFLOW_MAX\f[]
|
|
The max number that the overflow type (see the \f[B]PERFORMANCE\f[]
|
|
section) can hold.
|
|
Depends on \f[B]DC_LONG_BIT\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_BASE_MAX\f[]
|
|
The maximum output base.
|
|
Set at \f[B]DC_BASE_POW\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_DIM_MAX\f[]
|
|
The maximum size of arrays.
|
|
Set at \f[B]SIZE_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_SCALE_MAX\f[]
|
|
The maximum \f[B]scale\f[].
|
|
Set at \f[B]DC_OVERFLOW_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_STRING_MAX\f[]
|
|
The maximum length of strings.
|
|
Set at \f[B]DC_OVERFLOW_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_NAME_MAX\f[]
|
|
The maximum length of identifiers.
|
|
Set at \f[B]DC_OVERFLOW_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_NUM_MAX\f[]
|
|
The maximum length of a number (in decimal digits), which includes
|
|
digits after the decimal point.
|
|
Set at \f[B]DC_OVERFLOW_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B Exponent
|
|
The maximum allowable exponent (positive or negative).
|
|
Set at \f[B]DC_OVERFLOW_MAX\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B Number of vars
|
|
The maximum number of vars/arrays.
|
|
Set at \f[B]SIZE_MAX\-1\f[].
|
|
.RS
|
|
.RE
|
|
.PP
|
|
These limits are meant to be effectively non\-existent; the limits are
|
|
so large (at least on 64\-bit machines) that there should not be any
|
|
point at which they become a problem.
|
|
In fact, memory should be exhausted before these limits should be hit.
|
|
.SH ENVIRONMENT VARIABLES
|
|
.PP
|
|
dc(1) recognizes the following environment variables:
|
|
.TP
|
|
.B \f[B]DC_ENV_ARGS\f[]
|
|
This is another way to give command\-line arguments to dc(1).
|
|
They should be in the same format as all other command\-line arguments.
|
|
These are always processed first, so any files given in
|
|
\f[B]DC_ENV_ARGS\f[] will be processed before arguments and files given
|
|
on the command\-line.
|
|
This gives the user the ability to set up "standard" options and files
|
|
to be used at every invocation.
|
|
The most useful thing for such files to contain would be useful
|
|
functions that the user might want every time dc(1) runs.
|
|
Another use would be to use the \f[B]\-e\f[] option to set
|
|
\f[B]scale\f[] to a value other than \f[B]0\f[].
|
|
.RS
|
|
.PP
|
|
The code that parses \f[B]DC_ENV_ARGS\f[] will correctly handle quoted
|
|
arguments, but it does not understand escape sequences.
|
|
For example, the string \f[B]"/home/gavin/some dc file.dc"\f[] will be
|
|
correctly parsed, but the string \f[B]"/home/gavin/some "dc"
|
|
file.dc"\f[] will include the backslashes.
|
|
.PP
|
|
The quote parsing will handle either kind of quotes, \f[B]\[aq]\f[] or
|
|
\f[B]"\f[].
|
|
Thus, if you have a file with any number of single quotes in the name,
|
|
you can use double quotes as the outside quotes, as in \f[B]"some
|
|
\[aq]bc\[aq] file.bc"\f[], and vice versa if you have a file with double
|
|
quotes.
|
|
However, handling a file with both kinds of quotes in
|
|
\f[B]DC_ENV_ARGS\f[] is not supported due to the complexity of the
|
|
parsing, though such files are still supported on the command\-line
|
|
where the parsing is done by the shell.
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_LINE_LENGTH\f[]
|
|
If this environment variable exists and contains an integer that is
|
|
greater than \f[B]1\f[] and is less than \f[B]UINT16_MAX\f[]
|
|
(\f[B]2^16\-1\f[]), dc(1) will output lines to that length, including
|
|
the backslash newline combo.
|
|
The default line length is \f[B]70\f[].
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]DC_EXPR_EXIT\f[]
|
|
If this variable exists (no matter the contents), dc(1) will exit
|
|
immediately after executing expressions and files given by the
|
|
\f[B]\-e\f[] and/or \f[B]\-f\f[] command\-line options (and any
|
|
equivalents).
|
|
.RS
|
|
.RE
|
|
.SH EXIT STATUS
|
|
.PP
|
|
dc(1) returns the following exit statuses:
|
|
.TP
|
|
.B \f[B]0\f[]
|
|
No error.
|
|
.RS
|
|
.RE
|
|
.TP
|
|
.B \f[B]1\f[]
|
|
A math error occurred.
|
|
This follows standard practice of using \f[B]1\f[] for expected errors,
|
|
since math errors will happen in the process of normal execution.
|
|
.RS
|
|
.PP
|
|
Math errors include divide by \f[B]0\f[], taking the square root of a
|
|
negative number, attempting to convert a negative number to a hardware
|
|
integer, overflow when converting a number to a hardware integer, and
|
|
attempting to use a non\-integer where an integer is required.
|
|
.PP
|
|
Converting to a hardware integer happens for the second operand of the
|
|
power (\f[B]^\f[]) operator.
|
|
.RE
|
|
.TP
|
|
.B \f[B]2\f[]
|
|
A parse error occurred.
|
|
.RS
|
|
.PP
|
|
Parse errors include unexpected \f[B]EOF\f[], using an invalid
|
|
character, failing to find the end of a string or comment, and using a
|
|
token where it is invalid.
|
|
.RE
|
|
.TP
|
|
.B \f[B]3\f[]
|
|
A runtime error occurred.
|
|
.RS
|
|
.PP
|
|
Runtime errors include assigning an invalid number to \f[B]ibase\f[],
|
|
\f[B]obase\f[], or \f[B]scale\f[]; give a bad expression to a
|
|
\f[B]read()\f[] call, calling \f[B]read()\f[] inside of a
|
|
\f[B]read()\f[] call, type errors, and attempting an operation when the
|
|
stack has too few elements.
|
|
.RE
|
|
.TP
|
|
.B \f[B]4\f[]
|
|
A fatal error occurred.
|
|
.RS
|
|
.PP
|
|
Fatal errors include memory allocation errors, I/O errors, failing to
|
|
open files, attempting to use files that do not have only ASCII
|
|
characters (dc(1) only accepts ASCII characters), attempting to open a
|
|
directory as a file, and giving invalid command\-line options.
|
|
.RE
|
|
.PP
|
|
The exit status \f[B]4\f[] is special; when a fatal error occurs, dc(1)
|
|
always exits and returns \f[B]4\f[], no matter what mode dc(1) is in.
|
|
.PP
|
|
The other statuses will only be returned when dc(1) is not in
|
|
interactive mode (see the \f[B]INTERACTIVE MODE\f[] section), since
|
|
dc(1) resets its state (see the \f[B]RESET\f[] section) and accepts more
|
|
input when one of those errors occurs in interactive mode.
|
|
This is also the case when interactive mode is forced by the
|
|
\f[B]\-i\f[] flag or \f[B]\-\-interactive\f[] option.
|
|
.PP
|
|
These exit statuses allow dc(1) to be used in shell scripting with error
|
|
checking, and its normal behavior can be forced by using the
|
|
\f[B]\-i\f[] flag or \f[B]\-\-interactive\f[] option.
|
|
.SH INTERACTIVE MODE
|
|
.PP
|
|
Like bc(1), dc(1) has an interactive mode and a non\-interactive mode.
|
|
Interactive mode is turned on automatically when both \f[B]stdin\f[] and
|
|
\f[B]stdout\f[] are hooked to a terminal, but the \f[B]\-i\f[] flag and
|
|
\f[B]\-\-interactive\f[] option can turn it on in other cases.
|
|
.PP
|
|
In interactive mode, dc(1) attempts to recover from errors (see the
|
|
\f[B]RESET\f[] section), and in normal execution, flushes
|
|
\f[B]stdout\f[] as soon as execution is done for the current input.
|
|
.SH TTY MODE
|
|
.PP
|
|
If \f[B]stdin\f[], \f[B]stdout\f[], and \f[B]stderr\f[] are all
|
|
connected to a TTY, dc(1) turns on "TTY mode."
|
|
.PP
|
|
TTY mode is required for history to be enabled (see the \f[B]COMMAND
|
|
LINE HISTORY\f[] section).
|
|
It is also required to enable special handling for \f[B]SIGINT\f[]
|
|
signals.
|
|
.PP
|
|
The prompt is enabled in TTY mode.
|
|
.PP
|
|
TTY mode is different from interactive mode because interactive mode is
|
|
required in the bc(1)
|
|
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
|
|
and interactive mode requires only \f[B]stdin\f[] and \f[B]stdout\f[] to
|
|
be connected to a terminal.
|
|
.SH SIGNAL HANDLING
|
|
.PP
|
|
Sending a \f[B]SIGINT\f[] will cause dc(1) to stop execution of the
|
|
current input.
|
|
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[] section), it will
|
|
reset (see the \f[B]RESET\f[] section).
|
|
Otherwise, it will clean up and exit.
|
|
.PP
|
|
Note that "current input" can mean one of two things.
|
|
If dc(1) is processing input from \f[B]stdin\f[] in TTY mode, it will
|
|
ask for more input.
|
|
If dc(1) is processing input from a file in TTY mode, it will stop
|
|
processing the file and start processing the next file, if one exists,
|
|
or ask for input from \f[B]stdin\f[] if no other file exists.
|
|
.PP
|
|
This means that if a \f[B]SIGINT\f[] is sent to dc(1) as it is executing
|
|
a file, it can seem as though dc(1) did not respond to the signal since
|
|
it will immediately start executing the next file.
|
|
This is by design; most files that users execute when interacting with
|
|
dc(1) have function definitions, which are quick to parse.
|
|
If a file takes a long time to execute, there may be a bug in that file.
|
|
The rest of the files could still be executed without problem, allowing
|
|
the user to continue.
|
|
.PP
|
|
\f[B]SIGTERM\f[] and \f[B]SIGQUIT\f[] cause dc(1) to clean up and exit,
|
|
and it uses the default handler for all other signals.
|
|
The one exception is \f[B]SIGHUP\f[]; in that case, when dc(1) is in TTY
|
|
mode, a \f[B]SIGHUP\f[] will cause dc(1) to clean up and exit.
|
|
.SH COMMAND LINE HISTORY
|
|
.PP
|
|
dc(1) supports interactive command\-line editing.
|
|
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[] section), history is
|
|
enabled.
|
|
Previous lines can be recalled and edited with the arrow keys.
|
|
.PP
|
|
\f[B]Note\f[]: tabs are converted to 8 spaces.
|
|
.SH SEE ALSO
|
|
.PP
|
|
bc(1)
|
|
.SH STANDARDS
|
|
.PP
|
|
The dc(1) utility operators are compliant with the operators in the
|
|
bc(1) IEEE Std 1003.1\-2017
|
|
(“POSIX.1\-2017”) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
|
|
specification.
|
|
.SH BUGS
|
|
.PP
|
|
None are known.
|
|
Report bugs at https://git.yzena.com/gavin/bc.
|
|
.SH AUTHOR
|
|
.PP
|
|
Gavin D.
|
|
Howard <yzena.tech@gmail.com> and contributors.
|