The beauty of Ruby: Array Tricks

首先呢, 有兩個陣列…

ary1 = ["ruby", "coffeescript", "haskell", "lisp"]
ary2 = ["ruby", "python", "javascript", "lisp"]

大家都有, 沒什麼好說的

ary1.concat(ary2)
 => ["ruby", "coffeescript", "haskell", "lisp",
      "ruby", "python", "javascript", "lisp"]

ary1 + ary2
 => ["ruby", "coffeescript", "haskell", "lisp",
     "ruby", "python", "javascript", "lisp"]

差異在於 .concat 會影響 ary1, + 不會.

連續技:

ary1 << "clojure" << "perl" << "scala"
  => ["ruby", "coffeescript", "haskell", "lisp",
       "clojure", "perl", "scala"]

原理是因為<<會回傳加入新元素後的陣列.

有趣的來了

聯集(Union)

ary1 | ary2
 => ["ruby", "coffeescript", "haskell", "lisp",
     "python", "javascript"]

交集(Intersection)

ary1 & ary2
 => ["ruby", "lisp"]
{% endhighlight %}

* 差集(Difference)

```ruby
ary1 - ary2
 => ["coffeescript", "haskell"]

ary2 - ary1
 => ["python", "javascript"]