How to push items to ruby array using loop

Question

I am trying to create an array of dates using loop. But the loop is only pushing one date and when I query an array I see it's not an array, rather a list. Help.

date1 = '01-01-2019'.to_date
dates = []
count = 0
repeat = 3

while (count < repeat)
 count += 1
 date2 = date1 + count.month
 dates << date2
 puts dates
end

Expected results should be [01-02-2019, 01-03-2019, 01-04-2019].

However, if I use rails console, all I get are the dates in a list. If I raise dates.inspect in controller, I only get 01-02-2019.

How can I fix this?

FYI: terms list and array in Ruby are the exact synonyms. — Aleksei Matiushkin
– Aleksei Matiushkin, Commented Jan 6, 2019 at 16:46
dates = 3.times.map { |i| '01-01-2019'.to_date + i.months } does what you assumingly need. — Aleksei Matiushkin
– Aleksei Matiushkin, Commented Jan 6, 2019 at 16:48
I tested your piece of code and it's working fine. [Fri, 01 Feb 2019, Fri, 01 Mar 2019, Mon, 01 Apr 2019]. Check if the moment you are formatting the result is okay. — Kandy
– Kandy, Commented Jan 6, 2019 at 17:26
@Tiw, a small thing, but I think it's clearer to change map's receiver to, say, (1..repeat) or 1.upto(repeat). — Cary Swoveland
– Cary Swoveland, Commented Jan 6, 2019 at 18:45
Here's a hint: in Ruby, the answer to every question of the form "How do I X using loops" is "You don't, use Enumerable methods instead". If you ever find yourself writing a loop in Ruby, there's a 99.999% chance you are doing something wrong. — Jörg W Mittag
– Jörg W Mittag, Commented Jan 6, 2019 at 20:09

3limin4t0r · Accepted Answer · 2019-01-07 08:29:26Z

1

From your coding style it seems you're pretty new to Ruby. A more Ruby-like approach would be:

start_date = '01-01-2019'.to_date
repeat     = 3

dates = 1.upto(repeat).map { |count| start_date + count.months }
# or
dates = (1..repeat).map { |count| start_date + count.months }

Then to print the dates array use:

puts dates

As far as I can tell, your provided code should work. Keep in mind that puts prints arrays across multiple lines. If you want to display the contents of the array on a single line use p instead. The difference is that puts uses the to_s method while p uses the inspect method. Arrays passed to puts will be flattened and seen as multiple arguments instead. Every argument will get its own line.

puts [1, 2]
# 1
# 2
#=> nil

p [1, 2]
# [1, 2]
#=> [1, 2]

edited Jan 7, 2019 at 8:29

answered Jan 6, 2019 at 18:59

3limin4t0r

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Mayur Patil · Accepted Answer · 2019-01-07 04:20:40Z

0

Replace puts dates by puts "#{dates}". It will print array as expected like [01-02-2019, 01-03-2019, 01-04-2019].

answered Jan 7, 2019 at 4:20

Mayur Patil

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