Solved String Manipulation unix linux shell bash script

#string
while true
do
echo "Enter a choice"
echo "1) Compare two strings"
echo "2) concatenate two strings"
echo "3) length of string"
echo "4) Count occurence of string and word from a file"
echo "5) reverse a string"
echo "6) Put a string words  in an array"
read n

case $n in
1)
echo "enter 2 strings "
read s
read s2
if [ $s = $s2 ]
then
echo "Strings are equal"
else
       
echo "Strings are not equal"

    if [ $s \< $s2 ]
    then
    echo "String $s comes first"
    else
    echo "String $s2 comes first"
    fi
fi
;;
2) echo "enter 2 strings "
read s
read s2
s3="$s $s2"

echo $s3
;;
3)echo "enter a string"
read s

s3=` expr length $s `
echo "Length is $s3"
 ;;
4)
echo "enter a string"
read s

echo "enter a word to search in string"
read search_word

s2=` echo $s | grep -o $search_word | wc -l `

echo "The number of occurences is $s2"

 ;;
5)echo "Enter a string "
read s
s2=` echo $s | rev `
echo "Reversed String is $s2"
 ;;
6)
echo "Enter a string "
read s
declare -a arr
l=` echo $s| wc -c `
s="$s "
i=1
j=0
s3=""
S2=""
    while [ $i -le $l ]
    do
    s2=`echo $s |cut -c $i `
   
        if [ ! $s2 = " " ]
        then
        s3=$s3$s2
        else
        arr[j]=$s3
        s3=""
        j=` expr $j \+ 1 `
        fi

    i=` expr $i \+ 1 `
    done
echo "The words are:"
len=${#arr[@]}
u=0
while [ $u -lt $len ]
do
 echo "${arr[u]}"
u=` expr $u \+ 1 `
done
;;
*) exit 0 ;;
esac
done