Shell Programming and Scripting

i=1
while [ $i -le 3 ]
do
        echo "Valid entries are : benz bmw gms nissan polo"
        echo "Enter your choice $i / 3 :"
        read n

        case $n in
                benz|bmw|polo) country=DE;;
                nissan) country=JP ;;
                gms) country=USA ;;
                *) echo "wrong entry" ; let i-- ;;
        esac

        eval n$i=$n\' from \'$country
        let i++
done
echo "you have chosen :
-> $n1
-> $n2
-> $n3"

#!/bin/ksh
while :
do
        echo "Valid entries are : benz bmw gms nissan polo"
        echo "Please enter 3 of them (separated by a space) :"
        read a b c
        #short check
        if [[ ":$a:$b:$c:" = +(*::*) ]] ; then
                echo "At least on of the parameter is empty, try again"
        else

        # extended check
        for i in $a $b $c
        do
                case $i in
                        "benz"|bmw|gms|nissan|polo) : ;;
                        *) echo "ERROR : $i entry is not valid" ;;
                esac
        done
        break

        fi
done
echo "you have chosen :
-> $a
-> $b
-> $c"

*) echo "ERROR : $i entry is not valid" ;;

*) echo "ERROR : $i entry is not valid" ; continue 2;;

#!/bin/ksh
while :
do
        echo "Valid entries are : benz bmw gms nissan polo"
        echo "Please enter 3 of them (separated by a space) :"
        read a b c
        #short check
        if [[ ":$a:$b:$c:" = +(*::*) ]] ; then
                echo "At least on of the parameter is empty, try again"
        else
 
        # extended check
        for i in $a $b $c
        do
                case $i in
                        "benz"|bmw|gms|nissan|polo) : ;;
                        *) echo "ERROR : $i entry is not valid" ; continue 2 ;;
                esac
        done
        break
 
        fi
done
echo "you have chosen :
-> $a
-> $b
-> $c"