Python中运用random函数模拟用户登录验证码

'''
Created on 2017年9月8日

@author: Len
'''
import random
User_name,User_Pwd="Len","Len123"
check=''

def checking():
global check
for i in range(4):
cnumber=random.randint(0,4)
if cnumber == i:
x = chr(random.randint(65,90))

else:
x = random.randint(0,9)
check += str(x)

return check

def login():
username = input("请输入用户名：")
userpwd = input("请输入密码：")

while True:
if username == User_name and userpwd == User_Pwd :
print("用户名密码正确！")
checking()
print("验证码为：",check)
user_check=input("请输入验证码：")

if user_check==check:
print ("登陆成功！")
return
else:
print("输入错误!")
else:
print("输入错误，请重新输入！")

login()