预:
7> [I || <<I:1>> <= <<"abc">>].
[0,1,1,0,0,0,0,1,0,1,1,0,0,0,1,0,0,1,1,0,0,0,1,1]
8> [I || <<I:8>> <= <<"abc">>].
"abc"
(0)list_to_binary("www.Shank.kuang").
<<"www.Shank.kuang">>
binary:list_to_bin("www.Shank.kuang").
<<"www.Shank.kuang">>
byte_size(<<"www.Shank.me">>).
12
(1)返回一个二进制数据里指定位置（从 0 开始）的数据（整数的形式），
如果 Pos >= byte_size(Subject)，则会发生一个 badarg 的异常错误。
binary:at(<<"a", 1, "b", 2, "c", 3, "d", 4>>, 2).
98
binary:at(<<"a", 1, "b", 2, "c", 3, "d", 4>>, 3).
2
(2)binary:bin_to_list(<<"erlang">>).
"erlang"
% 从0开始
binary:bin_to_list(<<"erlang">>, {1 ,3}).
"rla"
binary:bin_to_list(<<"erlang">>, {1 ,33}).
** exception error: bad argument
in function binary:bin_to_list/2
called as binary:bin_to_list(<<"erlang">>,{1,33})
binary:bin_to_list(<<"erlang">>, 1, 3).
"rla"
(3)Binary = <<1, 2, 3, 4, 5, 6, 7, 8, 9, 10>>,
binary:copy(Binary).
<<1,2,3,4,5,6,7,8,9,10>>
(4)binary:copy(<<"www.Shank.kuang">>, 4).
<<"www.Shank.kuangwww.Shank.kuangwww.Shank.kuangwww.Shank.kuang">>
(5)返回一个二进制 Subject 的第一个字节的 ASCII 码。
如果二进制 Subject 的长度为 0，那么会有一个异常抛出
binary:first(<<"12345">>).
49
binary:last(<<"12345">>).
53
(6)Converts the binary digit representation, in big or little endian, of a positive integer in Subject to an Erlang integer().
注:representation of 算法表示;
默认是big端
binary:decode_unsigned(<<169,138,199>>).
11111111
binary:decode_unsigned(<<169,138,199>>,big).
11111111
binary:encode_unsigned(11111111,big).
<<169,138,199>>
(7)返回在列表二进制数据里最长的公共后缀(前缀)长度
binary:longest_common_suffix([<<"erlang">>, <<"fang">>]).
3
binary:longest_common_suffix([<<"erlang">>, <<"perl">>]).
0
binary:match(<<"abcde">>, [<<"bcde">>, <<"cd">>]).
{1,4}
binary:longest_common_prefix([<<"erlang">>,<<"ergonomy">>]).
2
binary:longest_common_prefix([<<"erlang">>,<<"perl">>]).
0
(8)这个binary:referenced_byte_size 是用于获取binary 数据的来源binary的大小:
eg:
1> A = binary:copy(<<1>>,100).
<<1,1,1,1,1 ...
2> byte_size(A).
100
3> binary:referenced_byte_size(A)
100
4> <<:10/binary,B:10/binary,/binary>> = A.
<<1,1,1,1,1 ...
5> byte_size(B).
10
6> binary:referenced_byte_size(B)
100
eg:2
113> Binary = <<1, 2, 3, 4, 5, 6, 7, 8, 9, 10>>,
113> <<_:4/binary, Bin:4/binary, _/binary>> = Binary,
113> binary:referenced_byte_size(Bin).
10
(9)
114> Bin = <<"www.dhq.me">>,
114> binary:split(Bin, <<".">>).
** exception error: no match of right hand side value <<"www.dhq.me">>
115> binary:split(<<"www.dhq.me">>, <<".">>).
[<<"www">>,<<"dhq.me">>]
116> binary:split(<<"www.kuang.feng.me.aab.">>, <<".">>).
[<<"www">>,<<"kuang.feng.me.aab.">>]
117> binary:split(<<1,255,4,0,0,0,2,3>>, [<<0,0,0>>,<<2>>]).
[<<1,255,4>>,<<2,3>>]
118>
1> binary:split(<<"banana">>,[<<"a">>],[{scope,{2,3}}]).
[<<"ban">>,<<"na">>]
2> binary:split(binary:part(<<"banana">>,{2,3}),[<<"a">>],[]).
[<<"n">>,<<"n">>]
(10)
Searches for the first occurrence of Pattern in Subject and returns
the position and length.
The function will return {Pos, Length} for the binary in Pattern
starting at the lowest position in Subject, Example:
binary:match(<<"abcdefghidg">>, [<<"bc">>,<<"cd">>],[]).
{1,2}
130> binary:match(<<"abcdefghidg">>, [<<"cd">>,<<"bc">>],[]).
{1,2}
有匹配了, 添加一个mnesia匹配的例子:
For example to find the names of all male persons with an age over 30 in table Tab do:
MatchHead = #person{name='$1', sex=male, age='$2', _='_'},
Guard = {'>', '$2', 30},
Result = '$1',
mnesia:select(Tab,[{MatchHead, [Guard], [Result]}]),
(11)
Constructs a new binary by replacing the parts in Subject matching Pattern with the content of Replacement.
If the matching sub-part of Subject giving raise to the replacement is to be inserted in the result, the option {insert_replaced, InsPos} will insert the matching part into Replacement at the given position (or positions) before actually inserting Replacement into the Subject. Example:
insert_replaced 属性的意思就是说:不直接替换了,把匹配到的
string按照 一个或者若干个位置插入到 用于替换的字符串的位置像
eg2是插入到 字符串"[]"的第一个位置,
eg4就是把匹配到的 "b"插入到字符串"[-]"的第一和第二个位置前面
1> binary:replace(<<"abcde">>,<<"b">>,<<"[]">>,[{insert_replaced,1}]).
<<"a[b]cde">>
2> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>,
[global,{insert_replaced,1}]).
<<"a[b]c[d]e">>
3> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[]">>,
[global,{insert_replaced,[1,1]}]).
<<"a[bb]c[dd]e">>
4> binary:replace(<<"abcde">>,[<<"b">>,<<"d">>],<<"[-]">>,
[global,{insert_replaced,[1,2]}]).
<<"a[b-b]c[d-d]e">>
1> Bin = <<1,2,3,4,5,6,7,8,9,10>>.
2> binary:part(Bin,{byte_size(Bin), -5}).
<<6,7,8,9,10>>
参考:
http://dhq.me/erlample/
http://www.erlang.org/doc/man/binary.html