Write a program which:
1. Asks the user to enter a positive integer greater than or equal to 0
2. Validates that the entry is a positive integer
3. Outputs the digits in reverse order with a space separating the digits
4. Outputs the even digits not in reverse order with a space separating the digits (consider zero to be even)
5. Outputs the odd digits not in reverse order with a space separating the digits
6. Allows user is to repeat/continue the program as many times as he/she wants
7. Restrictions:
a. You may not use global variables
8. Requirements:
a. You MUST have a function called validateUserInput. This function ensures that the user
input is valid and returns a string to main(). This function must take a string variable as
a parameter.
b. You MUST have a function called reverse. This must be a void function and should
output the digits in reverse order with a space separating them. This function must take
a string variable as a parameter.
c. You MUST have a function called evenDigits. This must be a void function and should
output the even digits not in reverse order with a space separating them. This function
must take a string variable as a parameter.
d. You MUST have a function called oddDigits. This must be a void function and should
output the odd digits not in reverse order with a space separating them. This function
must take a string variable as a parameter.
