Reversed sequence in Ruby-CodePudding

How do I return an array of integers from n to 1 where n>0? I wrote this code:

def reverse_seq(num)
reverse_seq = []
[].reverse { |num| num > 0; num  = 1 }
return []
end

Thanks!

CodePudding user response：

(1..5).to_a.reverse
#=> [5, 4, 3, 2, 1]

Or if you want to iterate over those elements in a next step anyway, use reverse_each

(1..5).reverse_each { |i| puts i }
#=> 5
    4
    3
    2
    1

CodePudding user response：

You could create an enumerator via downto that goes from n down to 1 and turn that into an array:

n = 5

n.downto(1).to_a
#=> [5, 4, 3, 2, 1]

or you could call Array.new with a block and calculate the value:

n = 5

Array.new(n) { |i| n - i }
#=> [5, 4, 3, 2, 1]

or you could traverse a range from n to 1 by passing -1 to step:

n = 5

(n..1).step(-1).to_a
#=> [5, 4, 3, 2, 1]