Erlang 实现十六进制字符串与二进制互转

 Erlang 实现十六进制字符串与二进制互转

%% from http://necrobious.blogspot.com/2008/03/binary-to-hex-string-back-to-binary-in.html

-module(hex).
-export([bin_to_hexstr/1,hexstr_to_bin/1]).

bin_to_hexstr(Bin) ->
  lists:flatten([io_lib:format("~2.16.0B", [X]) ||
    X <- binary_to_list(Bin)]).

hexstr_to_bin(S) ->
  hexstr_to_bin(S, []).
hexstr_to_bin([], Acc) ->
  list_to_binary(lists:reverse(Acc));
hexstr_to_bin([X,Y|T], Acc) ->
  {ok, [V], []} = io_lib:fread("~16u", [X,Y]),
  hexstr_to_bin(T, [V | Acc]);
hexstr_to_bin([X|T], Acc) ->
  {ok, [V], []} = io_lib:fread("~16u", lists:flatten([X,"0"])),
  hexstr_to_bin(T, [V | Acc]).

测试实例： 

Eshell V11.0  (abort with ^G)
1> c(hex).
{ok,hex}
2> H = hex:bin_to_hexstr(<<"你好，hello">>).
"C4E3BAC3A3AC68656C6C6F"
3> B =  hex:hexstr_to_bin(H).
<<"你好，hello">>
4>