What does "<<" exactly do in ruby?

Question

I am new to Ruby, so I am still learning several things. But, I do have good experience with Java and C.

I would like to know what this does exactly:

[ 'a','b', 'c' ].each_with_index {|item, index| result << [item, index] }

Specifically, I am interested in the <<. Some research tells me that it is used for bit shifting, but it's obvious that is not the case here, so what is it doing here?

Answer 1

The << operator is adding items to the result array in this case.

See " how to add elements to ruby array (solved)".

Answer 2

In Ruby, all the things which are operators in C/Java, like +, -, *, /, and so on, are actually method calls. You can redefine them as desired.

class MyInteger
  def +(other)
    42 # or anything you want
  end
end

Array defines the << method to mean "push this item on the end of this array". For integers, it's defined to do a bit shift.

Aside from Array, many other classes define << to represent some kind of "appending" operation.