Array Range

Learning Goals

• Demonstrate range
• Explain inclusive and exclusive range
• Generate an array with range

Introduction

A range is a data set with start and end values, and a sequence of values in between. Ranges can be found everywhere: The months January to December, the numbers 0 to 9, lines 50 through 67 in code, and so on. Ruby supports ranges and allows us to use ranges in a variety of ways.

Demonstrate Range

Ruby ranges are a set of values with a beginning and an end. The values in a range can be numbers, characters, strings or objects. It is written using start_point..end_point or start_point...endpoint literals. It provides flexibility to the code and reduces its size.

Parenthesis are not necessary to define a range, but if you want to call methods on your range you will need them.

The range class includes Enumerable, so you get all the powerful iteration methods without having to convert the range into an array.

for i in 0..3
    puts i
end

# => 0
# => 1
# => 2
# => 3

Explain Inclusive and Exclusive Range

Ruby has two operators available to generate a range of values. The inclusive two-dot (..) operator and the exclusive three-dot operator (...). The inclusive operator (..) includes both the first and last values in the range. The exclusive (...) range operator excludes the last value from the sequence. For example:

1..10    # Creates a range from 1 to 10 inclusive
1...10   # Creates a range from 1 to 9

Generate an Array With Range

The first and perhaps most natural use of ranges is to express a sequence. Sequences have a start point, an end point, and a way to produce successive values in the sequence. In order to convert a range to an array, we use the Ruby to_a method. For example:

(1..10).to_a -> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Conclusion

In this lesson we've discussed how ranges work in Ruby. With ranges, you can better implement your own objects that support range and sequential operations.

Resources

• Ruby Ranges: How Do They Work?
• Ruby Ranges
• Ranges in Ruby
• Ruby - Ranges