贴一下代码，例子是从别人那里直接抄来的：

-module(myudp).-export([start/0, client/1]).%% Serverstart() ->    spawn(fun() -> server(4000) end).    server(Port) ->    {ok, Socket} = gen_udp:open(Port, [binary, {active, false}]),    io:format("server opened socket:~p~n", [Socket]),    loop(Socket).    loop(Socket) ->    inet:setopts(Socket, [{active, once}]),    receive        {udp, Socket, Host, Port, Bin} ->            io:format("server received:~p~n", [Bin]),            gen_udp:send(Socket, Host, Port, Bin),            loop(Socket)    end.    %Client codeclient(N) ->    {ok, Socket} = gen_udp:open(0, [binary]),    io:format("client opened socket=~p~n", [Socket]),    ok = gen_udp:send(Socket, "localhost", 4000, N),    Value = receive                {udp, Socket, _, _, Bin} ->                    io:format("client received:~p~n", [Bin])                after 2000 ->                    0                end,    gen_udp:close(Socket),    Value.

尝试运行：

12> c("myudp").               {ok,myudp}13> myudp:start().server opened socket:#Port<0.2217><0.70.0>14> myudp:client("hello").client opened socket=#Port<0.2218>server received:<<"hello">>client received:<<"hello">>ok15> myudp:client("it's a long story").client opened socket=#Port<0.2219>server received:<<"it's a long story">>client received:<<"it's a long story">>ok16> myudp:client(<<"nothing">>).      client opened socket=#Port<0.2220>server received:<<"nothing">>client received:<<"nothing">>ok

话说，上面的直接使用引号的输入，和使用引号再使用尖括号的输入，效果是一样的。。。使用两个尖括号是什么？好像是在二进制的集合那里看到过这个符号？？