Write a program that uses an array of structures to hold contact information (first name, last name, address, phone number and email) for your friends. The program should allow the user to enter as many friends as the user wants. In this program do the following:
a. Create a function to add entries in the phone book.
b. Create a function to delete a specific entry (lookup based on the first name, assuming every entry has unique names) from the phone book.
(Hint: Use Dynamic Memory Allocation to shrink the array after deletion.)
c. Create a function to print valid phone book entries. Do not display phone book entries that are invalid or NULL (0). You can assume that all people have unique names.
d. Create a function to randomly select a friend from the phonebook for you to call.