python学习:利用循环语句完善输入设置

利用循环语句完善输入设置

使用for循环:

代码1:
_user = "alex"
_password = "abc123" for i in range(3):
username = input("Username:")
password = input("Password:")
if username == _user and password == _password:
print("Welcome %s login ..." % _user)
break
else:
print("Invalid username or password !")
代码2:
_user = "alex"
_password = "abc123" passed_authentication = False for i in range(3):
username = input("Username:")
password = input("Password:")
if username == _user and password == _password:
print("Welcome %s login ..." % _user)
passed_authentication = True #真,成立
break
else:
print("Invalid username or password !") if not passed_authentication:
print("您的输入次数已经达到上限!") #只有在True的情况下,条件成立
 代码3:
_user = "alex"
_password = "abc123" #passed_authentication = False for i in range(3):
username = input("Username:")
password = input("Password:")
if username == _user and password == _password:
print("Welcome %s login ..." % _user)
#passed_authentication = True #真,成立
break
else:
print("Invalid username or password !")
else:
print("您的输入次数已经达到上限!")#for循环正常结束,就可以执行下面的else语句 使用while循环:

代码:
_user = "alex"
_password = "abc123" counter = 0
while counter < 3:
username = input("Username:")
password = input("Password:")
if username == _user and password == _password:
print("Welcome %s login ..." % _user)
break
else:
print("Invalid username or password !")
counter += 1
else:
print("您的输入次数已经达到上限!")
 代码2
_user = "alex"
_password = "abc123" counter = 0
while counter < 3:
username = input("Username:")
password = input("Password:")
if username == _user and password == _password:
print("Welcome %s login ..." % _user)
break
else:
print("Invalid username or password !")
counter += 1
if counter == 3:
keep_going_choice = input("还想玩么?[y/n]")
if keep_going_choice == "y":
counter = 0
else:
print("您的输入次数已经达到上限!")
 
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