day05-06 continue语句、while循环

登录成功就break，登录不成功就打印

_user = "xiaoyanzi"
_passwd = "woaini"

pass_authentication = False
for i in range(3):
    username = input("username:")
    passwd = input("passwd:")


    if _user == username and _passwd == passwd:
        print("welcome to %s login"%username)
        pass_authentication = True
        break
    else:
        print("invalid username or passwd !!!")

if not pass_authentication:
    print("不洗脚的小燕子！！！")

可精简为：

_user = "xiaoyanzi"
_passwd = "woaini"


for i in range(3):
    username = input("username:")
    passwd = input("passwd:")


    if _user == username and _passwd == passwd:
        print("welcome to %s login"%username)

        break
    else:
        print("invalid username or passwd !!!")
else:
    print("不洗脚的小燕子！！！")

while循环（无限循环，又称死循环）：

while true:
print("中国人民万岁！")

输出结果为n个：

中国人民万岁！

_user = "xiaoyanzi"
_passwd = "woaini"


while true:  #死循环
    username = input("username:")
    passwd = input("passwd:")


    if _user == username and _passwd == passwd:
        print("welcome to %s login"%username)

        break
    else:
        print("invalid username or passwd !!!")
else:
    print("不洗脚的小燕子！！！")

将死循环改为有限循环：

_user = "xiaoyanzi"
_passwd = "woaini"

counter = 0
while counter < 3:
    username = input("username:")
    passwd = input("passwd:")


    if _user == username and _passwd == passwd:
        print("welcome to %s login"%username)
        
        break
    else:
        print("invalid username or passwd !!!")

    counter += 1


else:
    print("不洗脚的小燕子！！！")

三次输入错误之后，是否还想继续3次，再继续3次，效果：

_user = "xiaoyanzi"
_passwd = "woaini"

counter = 0
while counter < 3:
    username = input("username:")
    passwd = input("passwd:")


    if _user == username and _passwd == passwd:
        print("welcome to %s login"%username)
        True
        break
    else:
        print("invalid username or passwd !!!")

    counter += 1
   
     if counter == 3:
        keep_going_choice = input ("还想玩么？[y/n]")
        if keep_going_choice == "y":
            counter = 0
        


else:
    print("不洗脚的小燕子！！！")