Python学习：8.小项目之登录注册验证详解编程语言

try: 
    ..... 
except IOError: 
    ......

def login(username, password): 
""" 
用于用户名和密码的验证 
:param username:用户名 
:param paaword:密码 
:return:True,用户验证成功；False，用户验证失败 
""" 
try: 
f = open("users", "r", encoding="utf-8") 
for line in f: 
line = line.strip()  # 清除换行符 
# 无参数时移除两侧空格，换行符 
# 有参数时移除两侧指定的字符 
line_list = line.split("$") 
if line_list[0] == username and line_list[1] == password: 
# print("成功") 
return True 
return False 
except IOError: 
return False 
def register(username, password): 
""" 
注册用户 
1、打开文件 
2、用户名$密码 
:param username:用户名 
:param password:密码 
:return:True：注册成功； 
""" 
with open("users", "a", encoding="utf-8") as f: 
temp = "/n" + username + "$" + password 
f.write(temp) 
return True 
def user_exist(username): 
""" 
检测用户名是否存在 
:param username:要检测的用户名 
:return: True：用户名存在；False：用户名不存在 
""" 
# 一行一行的去查找，如果用户名存在，return True：False 
try: 
with open("users", "r", encoding="utf-8") as f: 
for line in f: 
line = line.strip() 
line_new = line.split("$") 
if line_new[0] == username: 
return True 
return False 
except IOError: 
return False 
def main(): 
while True: 
print("欢迎登录xxx系统") 
arg = input("1:登录，2：注册") 
if arg == "1": 
uer = input("请输入用户名:") 
pwd = input("请输入密码:") 
if login(uer, pwd): 
print("成功") 
break 
else: 
print("失败") 
elif arg == "2": 
user = input("请输入用户名:") 
pwd = input("请输入密码:") 
is_exist = user_exist(user) 
if is_exist: 
print("用户名已经存在，注册失败") 
else: 
if register(user, pwd): 
print("注册成功") 
continue 
else: 
print("注册失败") 
else: 
print("输入错误，请重新输入") 
main()