Write a shell script to perform operations like compare strings, concatenate strings, find length of a string, occurrence of word in a string and reverse a string - OS

i="y"
a=0
t=0
while [ $i = "y" ]
do
clear
echo "1.Compare 2 strings :"
echo "2.Concatanet string"
echo "3.Find length of string"
echo "4.Occurance of word"
echo "5.Reverse of string"
echo "6.Exit"
echo "Enter your choice"
read ch
case $ch in
1)echo "Enter first String"
read s1
echo "Enter second string "
read s2
if [ $s1 = $s2 ]
then
echo "Two strings are equal "else
echo "Two strings are not equal"
fi;;
2)echo "Enter one string "
read s1
echo "Enter second string "
read s2
echo $s1 $s2;;
3)echo "Enter any String"
read s1
t=`echo $s1|wc -c`
t=`expr $t - 1`
echo "Length of "$s1" is "$t;;
4)echo "Enter any String "
read s1
echo "Enter word u want to find occurance of:"
read c1
t=`echo $s1|wc -c`
t=`expr $t - 1`
echo "length "$t
while [ $t -ne 0 ]
do
temp=`echo $s1|cut -c $t`
temp2=`echo $temp2 $temp`
#echo $temp2
if [ $temp2 = $c1 ]
then
a=`expr $a + 1`
t=`expr $t - 1`
else
t=`expr $t - 1`
fi
done
echo "Occurance of "$c1" is "$a;;
5)echo "Enter any string :"
read s1
t=`echo $s1|wc -c`
t=`expr $t - 1`
echo "length "$t
while [ $t -ne 0 ]
do
temp=`echo $s1|cut -c $t`
echo $temp
temp2=`echo $temp2 $temp`
t=`expr $t - 1`
done
echo $temp2;;
6)exit;;
*)echo "Invalid choice";;
esac
echo "Do u want to continue ?"
read i
if [ $i != "y" ]
then
exit
fi
done