正则表达式

import re
str = '254.168.55.252'

#1.在一堆字符串里找ip 如：str = '323254.168.55.252d'

pattern = re.compile(u'(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)\.(25[0-5]|2[0-4]\d|[0-1]\d{2}|[1-9]?\d)')

print(pattern.search(str).group())

#输出：254.168.55.252
#2.判断ip格式是否正确
p = re.compile("^((?:(2[0-4]\d)|(25[0-5])|([01]?\d\d?))\.){3}(?:(2[0-4]\d)|(25[0-5])|([01]?\d\d?))$")
print(p.match(str).group())