Four Arithmetic Operation

Tp1: calculation of a formula with only a kind of operator

#! /bin/sh
n=$#
if [ $n -eq 0 ]
then
echo "Opération manquante"
exit
elif [ $n -eq 1 ]
then
echo "Opréation manquante"
else
res=$2
case $1 in
"add")
echo -n  $2
shift 2
while [ $# -ne 0 ]
do
echo -n "+$1"
res=`expr $res + $1`
shift
done
echo  "=${res}";;
"supp")
echo -n  $2
shift 2
while [ $# -ne 0 ]
do
echo -n "-$1"
res=`expr $res - $1`
shift
done
echo  "=${res}";;
"mult")
echo -n  $2
shift 2
while [ $# -ne 0 ]
do
echo -n "x$1"
res=`expr $res \* $1`
shift
done
echo  "=${res}";;
"div")
echo -n  $2
shift 2
while [ $# -ne 0 ]
do
echo -n "/$1"
if [ $1 -eq 0 ]
then
echo -e "\nDivision par 0 interdite"
exit
else
res=`expr $res / $1`
shift
fi
done
echo  "=${res}";;
*)
echo "Opération non traitée";;
esac
fi

Tp2: calculation of a formula without considering the priority of each operator

#! /bin/sh

if [ $# -eq 0 ]
then
echo " Opérande manquante"
exit
else
res=$1
echo -n "$1"

shift
while [ $# -ne 0 ]
do
case $1 in
"+")
echo -n " $1 $2"
res=`expr $res + $2`
shift 2
;;
"-")
echo -n " $1 $2"
res=`expr $res - $2`
shift 2
;;
"x")
echo -n " $1 $2"
res=`expr $res \* $2`
shift 2
;;
"/")
echo -n " $1 $2"
if [ $2 -eq 0 ]
then
echo  " ->Divivion par 0 interdite"
exit
else
res=`expr $res / $2`
shift 2
fi
;;
*)
echo  " $1 -> Opération non traitée"
exit
esac
done

echo " = $res"
fi

Tp3: calculation of a formula without brackets

#! /bin/sh
index=0

while [ $# -gt 0 ]
do
if [ $1 != x -a $1 != / ]
then
low_priority[$index]=$1
index=`expr $index + 1`
shift 1
else
case $1 in
"x")
pre_index=`expr $index - 1`
res=`expr ${low_priority[$pre_index]} \* $2`
low_priority[$pre_index]=$res
shift 2
;;

"/")
pre_index=`expr $index - 1`
res=`expr ${low_priority[$pre_index]} / $2`
low_priority[$pre_index]=$res
shift 2
;;
esac
fi
done

n=1
length=${#low_priority[@]}
end=`expr $length - 2`
res=${low_priority[0]}
while [ $n -le $end ]
do
case ${low_priority[$n]} in
"+")
nex_n=`expr $n + 1`
res=`expr $res + ${low_priority[$nex_n]}`
n=`expr $n + 2`;;
"-")
nex_n=`expr $n + 1`
res=`expr $res - ${low_priority[$nex_n]}`
n=`expr $n + 2`;;
*)
exit;;
esac
done

echo $res