[RAILS] A rough note about Ruby arrays and hash objects

A note about Ruby arrays and hash objects. Since I know the basics of arrays, I would like to make a note of how to write them unique to ruby.

When adding elements to an array

num = ["one"]
num << "two"
p num  # ["one", "two"]

Key and value definitions using hashes

numKey = { one: 1, two: 2 }
p numKey  # {:one=>1, :two=>2}
p numKey[:two]  # 2

Array definition in% notation

# numbers = ["one", "two", "three"]Same meaning
numbers = %W( one two three )
p numbers  # ["one", "two", "three"]

Extract the elements in the array one by one

%w[one two three].each do |num|
    p num
# "one"
# "two"
# "three"

Adds a value to the original array and returns a new array.

nums = %w[one two three four].map{ |num| "Numbers: #{num}" }
p nums  # ["Numbers: one", "Numbers: two", "Numbers: three", "Numbers: four"]

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