lua中的魔法字符转义问题

        lua中的魔法字符有( ) . % + - * ? [ ] ^ $ ，在表示它们时候要考虑用到转义，转义符号为%，但有些却不需要转义。下面我们通过实际代码来测试一下。

       首先来认识一个函数，string.find()查找目标模板在给定字符串中出现的位置，找返回起始和结束位置，没找到返回nil

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1(2","("))root@16d2a5728582:~/mapan# lua test.lua lua: test.lua:1: unfinished capturestack traceback:[C]: in function 'find'test.lua:1: in main chunk[C]: ?root@16d2a5728582:~/mapan# cat test.lua print(string.find("1(2","%("))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

( 需要转义

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1)2",")"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1)2","%)"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

) 不需要转义也能被find到，当然转义过了也没有问题

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1.2","."))root@16d2a5728582:~/mapan# lua test.lua 11root@16d2a5728582:~/mapan# cat test.lua print(string.find("1.2","%."))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

. 不需要转义能被find到，而且不会报错，但是返回的位置却不对，有点奇怪。加上转义字符%后，就成功返回了

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1%2","%"))root@16d2a5728582:~/mapan# lua test.lua lua: test.lua:1: malformed pattern (ends with '%')stack traceback:[C]: in function 'find'test.lua:1: in main chunk[C]: ?root@16d2a5728582:~/mapan# cat test.lua print(string.find("1%2","%%"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan#  

% 不转义会被报错，加了转义字符之后就返回了正确的结果

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1+2","+"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1+2","%+"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

+ 不转义不会报错，加上转义字符之后也没问题

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1-2","-"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1-2","%-"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

-  不转义不会报错，加上转义字符也没有问题

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1*2","*"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1*2","%*"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

* 不转义不会报错，加上转义字符也没问题

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1?2","?"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1?2","%?"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan#  

? 不转义不会报错，加上转义字符也没问题

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1[2","["))root@16d2a5728582:~/mapan# lua test.lua lua: test.lua:1: malformed pattern (missing ']')stack traceback:[C]: in function 'find'test.lua:1: in main chunk[C]: ?root@16d2a5728582:~/mapan# cat test.lua print(string.find("1[2","%["))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

[ 不加转义会报错，加上转义之后正常

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1]2","]"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# cat test.lua print(string.find("1]2","%]"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan# 

] 不加转义不会报错，加上转义之后也正常

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1^2","^"))root@16d2a5728582:~/mapan# lua test.lua 10root@16d2a5728582:~/mapan# cat test.lua print(string.find("1^2","%^"))root@16d2a5728582:~/mapan# lua test.lua 22root@16d2a5728582:~/mapan#  

^ 不加转义前打印结果不正常，加上转义之后打印结果正常

root@16d2a5728582:~/mapan# cat test.lua print(string.find("1$2","$"))root@16d2a5728582:~/mapan# lua test.lua 43root@16d2a5728582:~/mapan# 

$ 没加打印字符返回的结果不正常，加了之后打印结果就正常了

   这一些魔法字符，有些不需要转义，打印结果就正确；有些不转义，打印结果错误，但是不会报错；还有些直接报错。感觉挺有意思的，但是也有点不解，当然实际开发中，字符还是都应该加上转义。string.format()函数也会有类似的问题反馈