somearray = ["some", "thing"]
anotherarray = ["another", "thing"]
somearray + anotherarray # => ["some", "thing", "another", "thing"]
somearray.concat anotherarray # => ["some", "thing", "another", "thing"]
somearray.push(anotherarray).flatten # => ["some", "thing", "another", "thing"]
somearray.push *anotherarray # => ["another", "thing", "another", "thing"]
 

somearray = ["some", "thing"]
anotherarray = ["another", "thing"]
somearray + anotherarray # => ["some", "thing", "another", "thing"]
somearray.concat anotherarray # => ["some", "thing", "another", "thing"]
somearray.push(anotherarray).flatten # => ["some", "thing", "another", "thing"]
somearray.push *anotherarray # => ["another", "thing", "another", "thing"]
 

我很惊讶没有人提到reduce，当你有一个数组的数组时，它工作得很好:

lists = [["a", "b"], ["c", "d"]]
flatlist = lists.reduce(:+)  # ["a", "b", "c", "d"]

详细阐述@Pilcrow的答案，对于大型数组唯一合适的答案是concat(+)，因为它速度快，并且在循环中操作时不会分配一个新对象来进行垃圾回收。

下面是基准:

require 'benchmark'

huge_ary_1 = Array.new(1_000_000) { rand(5_000_000..30_000_00) }

huge_ary_2 = Array.new(1_000_000) { rand(35_000_000..55_000_00) }

Benchmark.bm do |bm|
  p '-------------------CONCAT ----------------'
  bm.report { huge_ary_1.concat(huge_ary_2) }

  p '------------------- PUSH ----------------'
  bm.report { huge_ary_1.push(*huge_ary_2)  }
end

结果:

       user     system      total        real
"-------------------CONCAT ----------------"
  0.000000   0.000000   0.000000 (  0.009388)
"------------------- PUSH ----------------"
  example/array_concat_vs_push.rb:13:in `block (2 levels) in <main>': stack level too deep (SystemStackError)

正如你所看到的，当数组足够大时，使用push会抛出ERROR:堆栈级别太深(SystemStackError)。

a = ["some", "thing"]
b = ["another", "thing"]

将b追加到a并将结果存储在a中:

a.push(*b)

or

a += b

在这两种情况下，a都变成:

["some", "thing", "another", "thing"]

但在前一种情况下，b的元素被追加到现有的a数组中，在后一种情况下，两个数组连接在一起，结果存储在a中。

a = ['a', 'b']
b = ['c', 'd']
arr = [a, b].flatten

这不会去除dups，但是

a|b

删除重复。