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Operating Systems OS X (Apple) A fixed point basic calculator for DASH. Post 303025604 by wisecracker on Tuesday 6th of November 2018 05:07:37 PM
Old 11-06-2018
Quote:
Originally Posted by Corona688
Here's a quick bash-only version for positive numbers. The trick is reading the values in. Once you do that the rest is straightforward.

Code:
DP=3
MOD=1000

function readnum {
        IFS="." read N FRAC <<<"$1"
        [ "$N" = "0" ] && N=""
        for((X=0; X<DP; X++))
        do
                D="${FRAC:$X:1}"
                [ -z "$D" ] && D="0"
                N="$N$D" # Prepend digits to N
        done
}

readnum "0.5"

echo "Integer $N is fixed point $((N/MOD)).$((N%MOD))"

I can see what you are doing, but forgive my ignorance; apart from the obvious bashisms, how do I use 'read' to input values directly from command line arguments without disk thrashing in POSIX 'dash'?
Everything MUST centre around 'dash' or POSIX 'sh'.
As for 'zsh', I can't be responsible for a non POSIX compliant shell.
This is the whole point of this [futile] exercise to see what is possible and what better than Fixed Point Arithmetic.
And I already assume a "fractional" part of 1000000000 and use "%.9f" to add any zeros to the end.
Anyhow I will try out your "MINUS" modification tomorrow.
Multiplication and division are harder still in 'dash'.

Back tomorrow.
HTH.

Bazza.
 

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SHELL-QUOTE(1)						User Contributed Perl Documentation					    SHELL-QUOTE(1)

NAME
shell-quote - quote arguments for safe use, unmodified in a shell command SYNOPSIS
shell-quote [switch]... arg... DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands or files with embedded white space or shell globbing characters safely. Here are a few examples. EXAMPLES
ssh preserving args When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and passes them to "$SHELL -c". This doesn't work as intended: ssh host touch 'hi there' # fails It creates 2 files, hi and there. Instead, do this: cmd=`shell-quote touch 'hi there'` ssh host "$cmd" This gives you just 1 file, hi there. process find output It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote: eval set -- `find -type f -print0 | xargs -0 shell-quote --` debug shell scripts shell-quote is better than echo for debugging shell scripts. debug() { [ -z "$debug" ] || shell-quote "debug:" "$@" } With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can. save a command for later shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are things the user can't pass through), you can do something like this: user_switches= while [ $# != 0 ] do case x$1 in x--pass-through) [ $# -gt 1 ] || die "need an argument for $1" user_switches="$user_switches "`shell-quote -- "$2"` shift;; # process other switches esac shift done # later eval "shell-quote some-command $user_switches my args" OPTIONS
--debug Turn debugging on. --help Show the usage message and die. --version Show the version number and exit. AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions. AUTHOR
Roderick Schertler <roderick@argon.org> perl v5.16.3 2010-06-11 SHELL-QUOTE(1)
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