#!/bin/sh
# nicenumber -- Given a number, shows it in comma-separated form.
# Expects DD and TD to be instantiated. Instantiates nicenum
# or, if a second arg is specified, the output is echoed to stdout.

nicenumber()
{
 # Note that we assume that '.' is the decimal separator in
 # the INPUT value to this script. The decimal separator in the output value is
 # '.' unless specified by the user with the -d flag

 integer=$(echo $1 | cut -d. -f1)       # left of the decimal
 decimal=$(echo $1 | cut -d. -f2)       # right of the decimal

 if [ $decimal != $1 ]; then
  # There's a fractional part, so let's include it.
  result="${DD:="."}$decimal"
 fi

 thousands=$integer

 while [ $thousands -gt 999 ]; do
  remainder=$(($thousands % 1000))  # three least significant digits

  while [ ${#remainder} -lt 3 ] ; do # force leading zeros as needed
   remainder="0$remainder"
  done

  thousands=$(($thousands / 1000))  # to left of remainder, if any
  result="${TD:=","}${remainder}${result}"  # builds right to left
 done

 nicenum="${thousands}${result}"
 if [ ! -z $2 ] ; then
  echo $nicenum
 fi
}

DD="." # decimal point delimiter, to separate integer and fractional values
TD="," # thousands delimiter, to separate every three digits

while getopts "d:t:" opt; do
 case $opt in
  d ) DD="$OPTARG"  ;;
  t ) TD="$OPTARG"  ;;
 esac
done
shift $(($OPTIND - 1))

if [ $# -eq 0 ] ; then
 echo "Usage: $(basename $0) [-d c] [-t c] numeric value"
 echo " -d specifies the decimal point delimiter (default '.')"
 echo " -t specifies the thousands delimiter (default ',')"
 exit 0
fi

nicenumber $1 1     # second arg forces nicenumber to 'echo' output

exit 0