What is the advantage of using the mutable buffer objects in boost ASIO compared to char arrays?

I'm designing/developing a UDP server application and plan to use boost. What are the mutable buffer objec开发者_Python百科ts for and what advantage is it over an standard char array?

Use fixed length buffers such as boost::array when you know a priori how much data you expect to receive or send. ASIO streambufs let you receive an unknown quantity of data. In particular, async_read_until requires you to use streambufs.