Ruby Range

A range in Ruby is an object that represents a sequence of values from a start to an end.

By default, a range includes a start and an end value and can be either inclusive (..) or exclusive (...).

# Create a range from 0 to 3 (inclusive)
numbers = 0..3

# Iterating through the range
numbers.each do |i|
  puts i
end

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Range Syntax

start..end      # includes end value  
start...end     # excludes end value

You can use integers, letters, or any object that can be compared and incremented to define the range.

Range Return Value

In Ruby, the .. and ... operators are used to create a Range object.

To access the values inside, you can convert this range into an array using the .to_a method.

Example 1: Inclusive Range

# Create a range from 0 to 3 (3 is included)
numbers = 0..3

# Convert to array and print it
puts numbers.to_a    # Output: [0, 1, 2, 3]

In this example, the range 0..3 is converted into an array using .to_a, which returns all values including the end.

Example 2: Exclusive Range

# Create an exclusive range that starts at 0 and ends before 4
numbers = 0...4
puts numbers.to_a    # Output: [0, 1, 2, 3]

# Creates an empty range
empty = 5...5
puts empty.to_a      # Output: []

Here, 0...4 creates a range that excludes 4, so the resulting array goes from 0 to 3.

Example 3: Character Ranges

# Lowercase letters
letters = 'a'..'d'
puts letters.to_a    # Output: ["a", "b", "c", "d"]

# Uppercase letters
caps = 'A'...'E'
puts caps.to_a       # Output: ["A", "B", "C", "D"]

In this example, 'a'..'d' includes 'd', while 'A'...'E' excludes 'E'.

Range in Loop

Ranges are often used in loops to repeat an action a specific number of times.

Here's an example using a for loop:

# Iterate the loop five times
for i in 0...5
  puts "#{i} Hello"
end

Output

0 Hello
1 Hello
2 Hello
3 Hello
4 Hello

Here, the range 0...5 runs the loop from 0 up to, but not including, 5.

Range in Conditions

Ranges can also be used to check if a value lies within a certain span. For example,

age = 25

if (18..30).include?(age)
    puts "You are a young adult."
end

Output

You are a young adult.

In this example, the condition evaluates to true because 25 lies within the range 18..30.

Range in Case Statement

Ranges are commonly used in case statements to simplify multiple comparisons. For example,

score = 78

case score
when 90..100
    puts "Grade A"
when 80...90
    puts "Grade B"
when 70...80
    puts "Grade C"
else
    puts "Grade D or lower"
end

Output

Grade C

Here, 78 matches the range 70...80, so it prints Grade C.

Beginless/Endless Ranges

Ruby also supports ranges with no beginning or end. For example,

# Beginless range: includes all values less than or equal to 10
range = (..10)
puts range.include?(5)     # true
puts range.include?(15)    # false

Here, (..10) matches any value ≤ 10.

# Endless range: includes all values greater than or equal to 5
range = (5..)
puts range.include?(100)   # true
puts range.include?(1)     # false 

Here, (5..) matches any value ≥ 5.

Common Ruby Range Methods

# From 1 to 10, step by 2
(1..10).step(2) do |i|
  puts i
end

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