1. 代码

import re

def is_ip(str):
    p = re.compile('^((25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(25[0-5]|2[0-4]\d|[01]?\d\d?)$')
    if p.match(str):
        return True
    else:
        return False


ip_str = "255.255.haha.255"

if is_ip(ip_str):
    print(ip_str,"is a IP!")
else:
    print(ip_str, "is not a IP!")