0-puts_recursion.c - Contains a function that prints a string, followed by a new line.
1-print_rev_recursion.c - Contains a function that prints a string in reverse.
2-strlen_recursion.c - Contains a function that returns the length of a string.
3-factorial.c - Contains a function that returns the factorial of a given number.
4-pow_recursion.c - Contains a function that returns the value of x raised to the power of y.
5-sqrt_recursion.c - Contains a function that returns the natural square root of a number.
6-is_prime_number.c - Contains a function that returns 1 if the input integer is a prime number, otherwise return 0.
100-is_palindrome.c - Checks if a string is palindrome or not.
101-wildcmp.c - Compares two strings and consider if they are identical.