print 1 至 100的奇數：

#print 奇數 for i in range(1,101,2) :　　# 2 為步長print("loop:",i)

打印小于50和大于70的數字：

for i in range(100):if i < 50 or i > 70:print(i)

三次輸入用戶信息：

_user = "eva" _passwd = "123"for i in range(3):username = input("Username:")password = input("Password:")if username == _user and password == _password:print("Welcome %s login..." %_user)breakelse:print("Invalid username or password!")

?三次輸入不成功后打印 You can't try any more!：

_user = "eva" _passwd = "123"passed_authentication = False #默認假，不成立（flag, 標志位）for i in range(3):username = input("Username:")password = input("Password:")if username == _user and password == _passwd:print("Welcome %s login..." %_user)passed_authentication = True #真，成立breakelse:print("Invalid username or password!")if not passed_authentication:print("You can't try any more！")

或者執行以下代碼：

_user = "eva" _passwd = "123"for i in range(3):username = input("Username:")password = input("Password:")if username == _user and password == _passwd:print("Welcome %s login..." %_user)break #break for后就不會執行最后那個else后的語句else:print("Invalid username or password!") else: #只要上面的for循環正常執行完畢，中間沒被打斷，就會執行else語句print("You can't try any more！")

或者執行以下代碼：

_user = "eva" _passwd = "123"counter = 0while counter < 3:username = input("Username:")password = input("Password:")if username == _user and password == _passwd:print("Welcome %s login..." %_user)break else:print("Invalid username or password!")counter += 1 else:print("You can't try any more!")

?

轉載于:https://www.cnblogs.com/evatan123/p/9191763.html

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