Reduce/inject for accumulation in Ruby - Mini Project: Build & Apply

Sum of Prices Using Reduce/Inject

📖 Scenario: You are managing a small store's inventory. Each product has a price, and you want to find out the total value of all products combined.

🎯 Goal: Build a Ruby program that uses inject to calculate the total price of all products in a dictionary.

📋 What You'll Learn

Create a hash called products with exact product-price pairs

Create a variable called total_price to hold the sum

Use inject on products.values to calculate the total

Print the total_price value

💡 Why This Matters

🌍 Real World

Calculating totals is common in shopping carts, budgets, and reports where you add many numbers together.

💼 Career

Knowing how to use <code>inject</code> helps you write clean and efficient Ruby code for data processing tasks.

1

Create the products hash

Create a hash called products with these exact entries: 'apple' => 100, 'banana' => 50, 'orange' => 75

Ruby

# Create the products hash with exact entries
# Your code here

Need a hint?

Use curly braces {} to create a hash with keys and values separated by =>.

2

Create the total_price variable

Create a variable called total_price and set it to 0

Ruby

products = { 'apple' => 100, 'banana' => 50, 'orange' => 75 }
# Create total_price variable and set to 0
# Your code here

Need a hint?

Just write total_price = 0 to start your sum at zero.

3

Use inject to sum the prices

Use inject on products.values to add all prices and assign the result to total_price

Ruby

products = { 'apple' => 100, 'banana' => 50, 'orange' => 75 }
total_price = 0
# Use inject on products.values to sum prices
# Your code here

Need a hint?

Use inject(0) { |sum, price| sum + price } to add all values starting from zero.

4

Print the total price

Write puts total_price to display the total price

Ruby

products = { 'apple' => 100, 'banana' => 50, 'orange' => 75 }
total_price = products.values.inject(0) { |sum, price| sum + price }
# Print the total_price
# Your code here

Need a hint?

Use puts total_price to print the number on the screen.