Building an Address Book Application with Hashes

Efficient Lookups: Hashes provide average O(1) time complexity for lookups, making retrieving contacts by name very fast.
Uniqueness: Hashes inherently ensure that each key (contact name) is unique, simplifying data consistency.
Readability: The syntax for accessing hash entries is intuitive, making the code easier to understand and maintain.
Flexibility: Ruby hashes are versatile, allowing us to extend the address book to store additional information, such as email addresses or addresses, if needed in the future.
Handling Collisions: Although hash functions may generate the same hash for different keys, Ruby handles these collisions efficiently and ensures consistent performance. This is crucial for maintaining the integrity of our address book entries.

Introduction

Welcome! In this lesson, we’ll explore creating a simple address book application using Ruby hashes. This exercise will strengthen your understanding of hashes in Ruby, specifically in adding, retrieving, and deleting entries.

By the end of this lesson, you’ll have a solid grasp of these fundamental operations and how they’re applied in practical programming tasks.

Introducing Methods to Implement

In this task, we’ll build three core methods to manage our address book:

add_contact(name, phone_number): Adds a new contact. If the contact already exists, it returns false and does not overwrite the number; otherwise, it adds the contact and returns true.
get_contact(name): Retrieves the phone number for a given name. If the contact does not exist, it returns nil.
delete_contact(name): Deletes a contact with the specified name. Returns true if the contact was successfully deleted and false if the contact does not exist.

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