Question

I am getting confused with the Array methods below. Can anyone help me understand how differently they work from each other with the help of simple snippet?

• array.sort and array.sort { | a,b | block }
• array.to_a and array.to_ary
• array.size and array.length
• array.reverse and array.reverse_each {|item| block }
• array.fill(start [, length] ) { |index| block } and
  array.fill(range) { |index| block }

Answer 1

Please read the documentation for Array.

sort:

a=[3,1,2]
a.sort              # => [1, 2, 3] 
a.sort{|a,b| b<=>a} # => [3, 2, 1] 

use the second one if you need some custom way to sort elements.

to_a vs. to_ary:

class Foo < Array;end
b=Foo[1,2]
b.to_ary.class # returns self
b.to_a.class   # converts to array

size and length are exactly the same.

reverse_each is pretty much the same as reverse.each.

If you want to fill only a part of the array, you can call Array.fill either with a range or start,length. Those are just different ways to achieve the same:

(["a"]*10).fill("b",2..7)
(["a"]*10).fill("b",2,6)

both return ["a", "a", "b", "b", "b", "b", "b", "b", "a", "a"].