Hello, Explorer! In this lesson, we will revisit Ruby loops, essential tools that simplify repetitive tasks.

Think of loops as a playlist on repeat. We will explore the Ruby looping universe and gain hands-on experience by applying loops to collections like arrays and strings.

Have you ever listened to your favorite song on repeat? That's what loops are about in programming: repeating a sequence of steps efficiently. Let’s take a look at how you can greet a list of friends using an each loop:

Ruby
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1friends = ['Alice', 'Bob', 'Charlie', 'Daniel']
2friends.each do |friend|
3  puts "Hello, #{friend}! Nice to meet you."
4end
5# Output:
6# Hello, Alice! Nice to meet you.
7# Hello, Bob! Nice to meet you.
8# Hello, Charlie! Nice to meet you.
9# Hello, Daniel! Nice to meet you.

Here, the loop iterates through the friends array, printing a personalized greeting for each name.

Ruby provides a for loop to iterate over any enumerable collection. While Rubyists often prefer methods like .each or .times for better readability, the for loop is straightforward and useful in certain cases.

Let's explore both of these options with 2 quick examples.

Here’s how you can print a range of numbers using a for loop:

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1for num in 0..4
2  puts num
3end
4# Output:
5# 0
6# 1
7# 2
8# 3
9# 4

In this example, the for loop iterates over the range 0..4, assigning each value to num on each iteration and printing it.

Alternatively, you can achieve the same result using a .times loop:

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15.times do |num|
2  puts num
3end
4# Output:
5# 0
6# 1
7# 2
8# 3
9# 4

Here, the loop runs 5 times, printing numbers from 0 to 4. The .times method is concise and works well when the iteration count is fixed.

The while loop executes code continuously until a condition becomes false. Here’s a simple example:

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1num = 0
2while num < 5
3  puts num
4  num += 1
5end
6# Output:
7# 0
8# 1
9# 2
10# 3
11# 4

Before each iteration, Ruby checks the condition (num < 5). If it's true, the code block runs; otherwise, the loop exits.

Ruby loops can directly work with collections, making it easy to handle elements of an array or string.

Ruby
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1fruits = ['apple', 'banana', 'cherry']
2fruits.each do |fruit|
3  puts fruit
4end
5# Output:
6# apple
7# banana
8# cherry

Here, the loop processes each element of the array and prints it.

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1word = 'hello'
2word.each_char do |letter|
3  puts letter
4end
5# Output:
6# h
7# e
8# l
9# l
10# o

Ruby's each_char method simplifies iterating over each character in a string by providing each character directly to the block, eliminating the need for manual indexing. It's ideal for tasks like counting vowels or transforming characters efficiently.

Loops are integral to programming. They are used in various scenarios, such as summing numbers in an array or counting specific characters in a string.

Ruby
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1numbers = [1, 2, 3, 4, 5]
2total = 0
3numbers.each do |num|
4  total += num
5end
6puts total
7# Output:
8# 15

In this example, the loop calculates the sum of all elements in the array.

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1text = 'hello'
2vowel_count = 0
3text.each_char do |letter|
4  vowel_count += 1 if 'aeiou'.include?(letter)
5end
6puts vowel_count
7# Output:
8# 2

By combining loops with conditional statements, you can implement complex logic and solve real-world problems efficiently.

Well done on mastering Ruby loops! We revisited looping fundamentals, explored Ruby's times, each, and while loops, and learned how to loop over collections like arrays and strings.

Now, it’s time to solidify your understanding through practice exercises. The more problems you solve, the more proficient you become. Keep practicing, and let’s continue our programming journey onward!