LDP/LDP/guide/docbook/abs-guide/ex61.sh

70 lines
1.1 KiB
Bash

#!/bin/bash
# Arabic number to Roman numeral conversion
# Range: 0 - 200
# It's crude, but it works.
# Extending the range and otherwise improving the script
# is left as an exercise for the reader.
# Usage: roman number-to-convert
LIMIT=200
E_ARG_ERR=65
E_OUT_OF_RANGE=66
if [ -z "$1" ]
then
echo "Usage: `basename $0` number-to-convert"
exit $E_ARG_ERR
fi
num=$1
if [ "$num" -gt $LIMIT ]
then
echo "Out of range!"
exit $E_OUT_OF_RANGE
fi
to_roman () # Must declare function before first call to it.
{
number=$1
factor=$2
rchar=$3
let "remainder = number - factor"
while [ "$remainder" -ge 0 ]
do
echo -n $rchar
let "number -= factor"
let "remainder = number - factor"
done
return $number
# Exercise for the reader:
# Explain how this function works.
# Hint: division by successive subtraction.
}
to_roman $num 100 C
num=$?
to_roman $num 90 LXXXX
num=$?
to_roman $num 50 L
num=$?
to_roman $num 40 XL
num=$?
to_roman $num 10 X
num=$?
to_roman $num 9 IX
num=$?
to_roman $num 5 V
num=$?
to_roman $num 4 IV
num=$?
to_roman $num 1 I
echo
exit 0