Question

arr = ["red","green","blue","yellow"]

arr.each do |colour|
  if colour == "red"
    colour = "green"
  end
end

puts arr.inspect

The above code outputs:

["red", "green", "blue", "yellow"]

but why not?

["green", "green", "blue", "yellow"]

I thought that colour was a reference to the current element in the array, and whatever i did to it would effect that array element?

Answer 1

When you’re inside the arr.each block, the colour variable is bound to one of the objects in the arr array.

However, as soon as you make the assignment colour = "green" in the block, now the colour variable is bound to a new object (namely a String with a value of "green"), and the original arr remains unaffected.

One way to achieve what you’re talking about would be:

arr.each_index do |i|
  arr[i] = "green" if arr[i] == "red"
end

which manipulates the array directly.