Correct way to populate an Array with a Range in Ruby

Question

I am working through a book which gives examples of Ranges being converted to equivalent arrays using their \"to_a\" methods

When i run the code in irb I get the fol

Answer 1

You can create an array with a range using splat,

>> a=*(1..10)
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

using Kernel Array method,

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

or using to_a

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

Answer 2

This works for me in irb:

irb> (1..4).to_a
=> [1, 2, 3, 4]

I notice that:

irb> 1..4.to_a
(irb):1: warning: default `to_a' will be obsolete
ArgumentError: bad value for range
        from (irb):1

So perhaps you are missing the parentheses?

(I am running Ruby 1.8.6 patchlevel 114)

Answer 3

Sounds like you're doing this:

0..10.to_a

The warning is from Fixnum#to_a, not from Range#to_a. Try this instead:

(0..10).to_a

Answer 4

Check this:

a = [*(1..10), :top, *10.downto( 1 )]

Answer 5

I just tried to use ranges from bigger to smaller amount and got the result I didn't expect:

irb(main):007:0> Array(1..5)
=> [1, 2, 3, 4, 5]
irb(main):008:0> Array(5..1)
=> []

That's because of ranges implementations.
So I had to use the following option:

(1..5).to_a.reverse

Answer 6

This is another way:

irb> [*1..10]

=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]