如何用erlang badarg解决问题？

Question

我在 Eclipse 中运行了下面的代码。代码已编译，并在 Eclipse 工作区的

.txt

文件夹中创建

scr

文件，并将数据头传递给第一个

io:format

，但

second io:format

抛出错误参数错误，我不知道如何解决。

%% @author PC
%% @doc @todo Add description to pingping.

-module(pingping).
-export([run/2, run/3]).
-include("conf.hrl").

run(DataSize, R) ->
    OutFileLocation = "out_cerl_pingping.txt",
    case file:open(OutFileLocation, [append]) of
        {error, Why} ->
            ?ERR_REPORT("L'archivio non esiste!", Why);
        {ok, OutFile} ->
            run(DataSize, R, OutFile)
    end.

run(DataSize, R, OutFile) ->
    Data = generate_data(DataSize),
    Self = self(),
    SpawnStart = time_microseg(),
    P1 = spawn(fun() -> pingping(Data, Self, R) end),
    P2 = spawn(fun() -> pingping(Data, Self, R) end),
    SpawnEnd = time_microseg(),
    TimeStart = time_microseg(),
    P1 ! {init, self(), P2},
    P2 ! {init, self(), P1},
    finalize(P1),
    finalize(P2),
    TimeEnd = time_microseg(),
    TotalTime = TimeEnd - TimeStart,
    SpawnTime = SpawnEnd - SpawnStart,
    printResult(Data, R, TotalTime, SpawnTime, OutFile).

pingping(_, Parent, 0) ->
    Parent ! {finish, self()};
pingping(Data, Parent, R) ->
    receive
        {init, Parent, Peer} ->
            Peer ! {self(), Data},
            pingping(Data, Parent, R-1);
        {Peer, _} ->
            Peer ! {self(), Data},
            pingping(Data, Parent, R-1)
    end.

finalize(Pid) ->
    receive
        {finish, Pid} -> ok
    end.

printResult(Data, R, Time_exec, Time_spawn, OutFile) ->
    FormatH = "~-9s\t ~-13s\t ~-22s\t ~-11s\t ~-10s~n",
    Header = ["#bytes", "#repetitions", "exec_time[microsec]", "MBytes/sec", "spawn_time"],
    io:format(OutFile, FormatH, Header),
    MBps = bandwidth_calc(Data, Time_exec),
    FormatD = "~-9w\t ~-13w\t ~-22f\t ~-11f\t ~-3f~n",
    io:format(OutFile,FormatD, [size(Data), R, Time_exec, MBps, Time_spawn ]).

bandwidth_calc(Data, Time) ->
    Megabytes = (size(Data) / math:pow(2, 20)),
    Seconds = (Time * 1.0e-6),
    Megabytes / Seconds.

generate_data(Size) -> generate_data(Size, []).
generate_data(0, Bytes) ->
    list_to_binary(Bytes);
generate_data(Size, Bytes) ->
    generate_data(Size - 1, [1 | Bytes]).

time_microseg() ->
    {MS, S, US} = now(),
    (MS * trunc(1.0e+12)) + (S * trunc(1.0e+6)) + US.

%-define(OUT_FILE, "erl_out.txt").

-define(ERR_REPORT(Msg, Reason), io:format("%%%%%%%%%%%%%% ERROR %%%%%%%%%%%%%%\n" ++
                     "Msg: ~s\n" ++
                     "Reason: ~s\n\n", [Msg, Reason])).

Answer 1

您的代码无法编译，因为未显示

conf.hrl

包含文件，所以我猜测它提供了底部提供的

ERR_REPORT

宏。您没有包含有关如何运行代码的说明，因此我猜测并调用了

pingping:run(3, 3).

，这导致了 Erlang/OTP 26.1 下的此错误：

** exception error: bad argument
     in function  io:format/3
        called as io:format(<0.95.0>,"~-9w\t ~-13w\t ~-22f\t ~-11f\t ~-3f~n",
                            [3,3,23,0.12439230213994565,6])
        *** argument 3: element 3 must be of type float
                        element 5 must be of type float

错误消息给了我们答案：您正在尝试将整数打印为浮点数。更改此行：

FormatD = "~-9w\t ~-13w\t ~-22f\t ~-11f\t ~-3f~n",

为了更正元素 3 和 5 的格式，请执行以下操作：

FormatD = "~-9w\t ~-13w\t ~-22w\t ~-11f\t ~-3w~n",

导致

pingping:run(3, 3)

返回

ok

以及包含以下内容的

out_cerl_pingping.txt

文件：

#bytes       #repetitions    exec_time[microsec]     MBytes/sec      spawn_time
3            3               15                      0.190735        5