[ruby] Correct way to populate an Array with a Range in Ruby

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 following warning

 warning: default `to_a' will be obsolete

What is the the correct alternative to using to_a?

are there alternate ways to populate an array with a Range?

This question is related to ruby syntax

The answer is


This is another way:

irb> [*1..10]

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

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)


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

Check this:

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

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

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)


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

Check this:

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

This is another way:

irb> [*1..10]

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

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

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

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

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)