How do this
Print the decimal, octal and hexadecimal values of all characters between the start
and stop characters entered by a user. For example, if the user enters an a and z, the
program should print all the characters between a and z and their respective
numerical values. Make sure that the second character entered by the user occur
later in the alphabet than the first character. If it does not, write a loop that
repeatedly asks the user for a valid second character until one is entered.