Question

我想接受以s开头的字符串而不是下一个字符（无论它是什么）必须在脚本中再次被包含两次（但不能少于，不多），并且在此char之前不能是反斜杠。所以：

s(.)[now some chars except (.) and not ending with \]\1[some chars but not (.) and not ending with \]\1[some chars but not (.)]

\ 1和（。）和s是正则表达式的真正部分

Answer 1

我认为egrep不会削减它你需要一个可以做前瞻断言的grep，这就是原因：

/^ s (.) (?:(?:\\.|(?!\1).)+\1){2} (?:\\.|(?!\1).)+ $/xs

/^             # Begin of string
     s
     (.)                # capture first char after 's'
     (?:                # Begin Grp
         (?: \\.          # begin grp, escaped anything
           | (?!\1).        # OR, any char that is not (.)
         )+               # end grp, do this more than once
         \1               # Followed by (.)
     ){2}               # End Grp, do this exactly twice

     (?: \\.            # begin grp, escaped anything
       | (?!\1).           # OR, anchar that is not (.)
     )+                 # end grp, do this more than once

 $/xs         # End of string, x and s modifiers

如何告诉egrep哪些字符不接受

1 个答案: