a="this is"
b=list(a)
print(b)回车
['t', 'h', 'i', 's', ' ', 'i', 's']

a="this is"
b=a.split()
print(b)回车
['this', 'is']
#以上是b=list(a)和b=a.split的区别


#如何用find找到第二个i的索引
a="this is i i"
b=0
count=1
while True:
b=a.find("i",b)
if b==-1:
break
if count>1:
break
b+=1
count+=1
print(b)回车
5


#用正则匹配邮箱是否正确
import re
e="854@qq.com"
a=re.findall(r"[0-9a-zA-Z]+@[0-9a-zA-Z]+.[a-z]+",e)
print(a)


#用正则匹配身份证是否正确
import re
e="441502199402233049"
a=re.findall(r"[1-8]\d{5}(?:19[0-9][0-9]|20[0-2][0-1]|20[0-1][2-9])(?:0[1-9]|1[0-2])(?:0[1-9]|1[0-9]|2[0-9]|3[0-1])[0-9X]+",e)
print(a)