FILE 0-puts_recursion.c is a function that prints a string.
FILE 1-print_rev_recursion.c is a function that prints a string in reverse.
FILE 2-strlen_recursion.c is a function that returns the length of a string.
FILE 3-factorial.c is a function that returns the factorial of a given number.
FILE 4-pow_recursion.c is function that returns the value of x raised to the power of y.
FILE 5-sqrt_recursion.c is a function that returns the natural square root of a number.
FILE 6-is_prime_number.c is a function that returns 1 if the input integer is a prime number.
FILE 100-is_palindrome.c is a function that returns 1 if a string is a palindrome and 0 if not.
FILE 101-wildcmp.c is a function that compares two strings and returns 1 if the strings can be considered identical, otherwise return 0.