Question

我的代码如下：

10> clients_size:init().
{state,[]}

11> clients_size:size().
** exception error: bad argument
     in function  length/1
        called as length(2)
     in call from orddict:size/1 (orddict.erl, line 65)
     in call from clients_size:size/0 (clients_size.erl, line 10)

clients_size.erl

-module(clients_size).
-export([init/0, size/0]).
-record(state, {clients}). 

init() ->
    #state{clients=orddict:new()}.


size()->
    Size_of = orddict:size(#state.clients),
    io:format("size ~p ~n ",[Size_of]).

我知道它是空的，但我仍然认为它会显示为0.

Answer 1

你没有将任何变量传递给orddict：size（）。

state.clients返回一个整数 - 处于记录状态的字段“clients”。

Answer 2

我明白了！

-module(clients_size).
-export([init/0, size/1]).
-record(state, {clients}). 

init() ->
    #state{clients=orddict:new()}.


size(S)->
    Size_of = orddict:size(S#state.clients),
    io:format("reference:size ~p ~n ",[Size_of]).

运行：

19> c(clients_size).
{ok,clients_size}
20> X = clients_size:init().
{state,[]}
21> clients_size:size(X).   
reference:size 0 
 ok

Erlang：orddict：size（）函数用于记录？

2 个答案: