Python学习日记-7-简单用户登录系统

方法一：

_user = "xiaoran"
_passward = "123456"

pass_authenication = False  #标志位初始为假

for i in range(3):    # i=0,1,2
    user = input("Username:")
    passward = input("Passward:")
    if user == _user and passward == _passward:
        print("welcome %s login" %user)
        pass_authenication = True   #标志位为真
        break
    else:
        print("please input again")

if not pass_authenication:    #如果标志位为假
    print("您已经连续输入错误三次！！！")

方法二：

_user = "xiaoran"
_passward = "123456"
for i in range(3):
    user = input("Username:")
    passward = input("Passward:")
    if user == _user and passward == _passward:
        print("welcome %s login" %user)
        break                           #中断，跳出
    else:
        print("please input again")
else:                                   #循环执行完且中间没有被中断时，执行
    print("您已经连续输入错误三次！！！")

方法三：

_user = "xiaoran"
_passward = "123456"
count = 0

while count < 3:
    user = input("Username:")
    passward = input("Passward:")
    if user == _user and passward == _passward:
        print("welcome %s login" %user)
        break                           #中断，跳出
    else:
        print("please input again")
    count += 1
    if count == 3:                      #附加功能：每循环三次询问是否继续
        choice = input("是否继续输入？[y/n]")
        if choice == 'y':
            count = 0
else:                                   #循环执行完且中间没有被中断时，执行
    print("您已经连续输入错误三次！！！")