python学习之re 18 subn(pattern, repl, string, count=0, flags=0)

re. subn ( pattern,  repl,  string,  count=0,  flags=0 )

Perform the same operation as sub(), but return a tuple (new_string, number_of_subs_made).

Changed in version 3.1: Added the optional flags argument.

Changed in version 3.5: Unmatched groups are replaced with an empty string.

翻译：操作和sub类似，但是返回的是一个元组（新串，替换的次数）

import re

string1 = "abcxxd"
print(re.subn("(x*)","-",string1))

('-a-b-c--d-', 6)