erlang 语法摘记2

5.4.3块表达式
    begin
      Expr1,
      .....,
      ExprN
    end     只允许单表达式，却需要一串表达式
5.4.4 布尔类型     not and or xor
5.4.8 epp 预处理  compile:file(M,['p'])   M.erl  M.p(此文件)
5.4.9 转义符  \b \d \e \f \n \r \s  \t  \v    \NNN \NN \N 八进制 N是0-7
      \^a....\^z   or   \^A...\^Z      ctrl+A到ctrl+Z
      \'  \"  \\    \C          ~w 打印原始结果    io:format("~w", [""]).
5.4.10 -> 表达式序列由逗号，分开的表达式   序列值为最后一个表达式的值
     export
     import
     include
5.4.13 列表操作符：  ++   --
5.4.14 宏：宏处理形如 ？Macroname ?MacroName 的表达式  ？FILE ？MODULE ？LINE
       ?FILE   扩展为当前文件名；
       ?MODULE 扩展为当前模块名； ！切记
       ?LINE   扩展为当前行号；

       宏内部控制流程




keysearch 用法！
30> lists:keysearch(user,1,[{"uname","zdx3578"},{"passwd","1"},{"url","undefined"}] ).
false
31> lists:keysearch(uname,1,[{"uname","zdx3578"},{"passwd","1"},{"url","undefined"}] ).
false
32> lists:keysearch("uname",1,[{"uname","zdx3578"},{"passwd","1"},{"url","undefined"}] ).
{value,{"uname","zdx3578"}}
33> lists:keysearch("passwd",1,[{"uname","zdx3578"},{"passwd","1"},{"url","undefined"}] ).
{value,{"passwd","1"}}
34> lists:keysearch("url",1,[{"uname","zdx3578"},{"passwd","1"},{"url","undefined"}] ).
{value,{"url","undefined"}}
35> lists:keysearch(4,2,[{1,a,1,4,45},{4,4}]).
{value,{4,4}}