Python-从正则表达式生成指定长度的随机字符串

Question

My string length is allowed not more than 255 characters. The following Regular expression can be taken for example-

^([a-zA-Z0-9]{1}((-|[a-zA-Z0-9])*[a-zA-Z0-9])*[.])*[a-zA-Z]{1}((-|[a-zA-Z0-9])*[a-zA-Z0-9])*\.?$

i am using exrex.getone(regular_expression) function for generating strings where i can't control generated string length.
How to generate a string of intended length which satisfy the Regular Expression also ?
Till now i have not seen any answer satisfying this condition.

Answer 1

From exrex website:

There are regular expressions with infinite matching strings (eg.: [az]+ ), in these cases exrex limits the maximum length of the infinite parts.

and the code itself:

418 def getone(regex_string, limit=20): 
419     """Returns a random matching string to a given regular expression 
420     """ 
421     return _randone(parse(regex_string), limit) 

So there's a limit keyword. I couldn't tell for sure if this limits the entire string or each infinite part, but I think it's the latter. Try limiting this to something smaller, like 4.