Good! There are a bunch of really useful Ruby methods that take blocks. One we haven’t covered yet is collect.
The collect method takes a block and applies the expression in the block to every element in an array. Check it out:
If we look at the value of my_nums, though, we’ll see it hasn’t changed:
This is because .collect returns a copy of my_nums, but doesn’t change (or mutate) the original my_nums array. If we want to do that, we can use .collect! with an exclamation point:
Recall that the ! in Ruby means “this method could do something dangerous or unexpected!” In this case, it mutates the original array instead of creating a new one.
Instructions
We’ve created an array, fibs, and placed the first ten Fibonacci numbers in it.
Create a new variable, doubled_fibs, and set it equal to the result of calling fibs.collect. The block you pass to .collect should double each Fibonacci number, similar to the example above.
puts doubled_fibs if you want to see the final contents of the array.