Create array of n items based on integer value
RubyRuby Problem Overview
Given I have an integer value of, e.g., 10.
How can I create an array of 10 elements like [1,2,3,4,5,6,7,8,9,10]?
Ruby Solutions
Solution 1 - Ruby
You can just splat a range:
[*1..10]
#=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Ruby 1.9 allows multiple splats, which is rather handy:
[*1..3, *?a..?c]
#=> [1, 2, 3, "a", "b", "c"]
Solution 2 - Ruby
yet another tricky way:
> Array.new(10) {|i| i+1 }
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Solution 3 - Ruby
About comments with tricky methods:
require 'benchmark'
Benchmark.bm { |x|
x.report('[*..] ') do
[*1000000 .. 9999999]
end
x.report('(..).to_a') do
(1000000 .. 9999999).to_a
end
x.report('Array(..)') do
Array(1000000 .. 9999999)
end
x.report('Array.new(n, &:next)') do
Array.new(8999999, &:next)
end
}
Be careful, this tricky method Array.new(n, &:next) is slower while three other basic methods are same.
user system total real
[*..] 0.734000 0.110000 0.844000 ( 0.843753)
(..).to_a 0.703000 0.062000 0.765000 ( 0.843752)
Array(..) 0.750000 0.016000 0.766000 ( 0.859374)
Array.new(n, &:next) 1.250000 0.000000 1.250000 ( 1.250002)
Solution 4 - Ruby
def array_up_to(i)
(1..i).to_a
end
Which allows you to:
> array_up_to(10)
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Solution 5 - Ruby
You can do this:
array= Array(0..10)
If you want to input, you can use this:
puts "Input:"
n=gets.to_i
array= Array(0..n)
puts array.inspect