Hashes (Key-Value Mappings)

💎 Ruby Lesson 7 Intermediate

Hashes store data in key-value pairs. In modern Ruby, symbols are preferred as keys to optimize memory efficiency.

1 Rocket Syntax vs. Symbol Key Shorthands

Ruby hashes support two key syntaxes:

Rocket Syntax (`=>`): Traditional syntax. Can use any object type as keys: `:name => "Bob"`.
Symbol Shorthand Syntax: Modern syntax. Syntactically cleaner and automatically processes keys as symbols: `name: "Bob"`.

2 Hash Operations Code

Let's run a program declaring hashes, accessing values, and deleting keys:

Ruby — Hashes ▶ Run Code

# Modern Symbol key shorthand syntax
student = {
  name: "Alice",
  age: 21,
  gpa: 3.8
}

puts "Student Name: #{student[:name]}" # Accessed using symbol
puts "Keys in Hash: #{student.keys}"

# Fetch with default fallback
rating = student.fetch(:rating, "No Rating Available")
puts "Rating: #{rating}"

# Delete key
student.delete(:age)
puts "Updated Hash: #{student.inspect}"

3 Code Challenge

Challenge: Write a program that stores product items and prices in a hash. Write a loop to iterate through the hash, printing each product name and its price.