Calling specific element from array not returning (Ruby)

Your code should be :

def morse_code(str)
  string = []
  string.push(*str.split(' '))
  puts string
  p string[2]
end

morse_code("what is the dog" )
# >> what
# >> is
# >> the
# >> dog
# >> "the"

str.split(' ') is giving ["what", "is", "the", "dog"], and you are pushing this array object to the array string. Thus string became [["what", "is", "the", "dog"]]. Thus string is an array of size 1. Thus if you want to access any index like 1, 2 so on.., you will get nil. You can debug it using p(it calls #inspect on the array), BUT NOT puts.

def morse_code(str)
  string = []
  string.push(str.split(' '))
  p string
end

morse_code("what is the dog" )
# >> [["what", "is", "the", "dog"]]

With Array, puts works completely different way than p. I am not good to read MRI code always, thus I take a look at sometime Rubinious code. Look how they defined IO::puts, which is same as MRI. Now look the specs for the code

it "flattens a nested array before writing it" do
    @io.should_receive(:write).with("1")
    @io.should_receive(:write).with("2")
    @io.should_receive(:write).with("3")
    @io.should_receive(:write).with("\n").exactly(3).times
    @io.puts([1, 2, [3]]).should == nil
  end

  it "writes nothing for an empty array" do
    x = []
    @io.should_receive(:write).exactly(0).times
    @io.puts(x).should == nil
  end

  it "writes [...] for a recursive array arg" do
    x = []
    x << 2 << x
    @io.should_receive(:write).with("2")
    @io.should_receive(:write).with("[...]")
    @io.should_receive(:write).with("\n").exactly(2).times
    @io.puts(x).should == nil
  end

We can now be sure that, IO::puts or Kernel::puts behaves with array just the way, as Rubinious people implemented it. You can now take a look at the MRI code also. I just found the MRI one, look the below test

  def test_puts_recursive_array
    a = ["foo"]
    a << a
    pipe(proc do |w|
      w.puts a
      w.close
    end, proc do |r|
      assert_equal("foo\n[...]\n", r.read)
    end)
  end