まくまくRubyノート
配列を結合する
arr = [1, 2, 3]
arr += [4] # => [1, 2, 3, 4]
arr += [5, 6, 7] # => [1, 2, 3, 4, 5, 6, 7]
arr = [1, 2, 3]
arr2 = arr + [4] # => [1, 2, 3, 4]
arr2 = arr + [4, 5, 6] # => [1, 2, 3, 4, 5, 6]
+ の右側は要素が 1 つだけの場合も [] で囲む必要があります。
