python循环最后的else

python的while和for循环之后，可以跟随else。如：while....else和for...else.

但是这个else中语句的执行是有条件的，如果是执行了break从循环中中断的话，else是不执行的。

循环的条件正常结束后，才会执行else中语句。

以下例子：

第一个，每次循环正常结束后都会有两个提示出现：

#!/usr/bin/python
# -*-coding:utf-8 -*-
import datetime

for i in range(1,5):
    name = input("please input your name:")
    pwd = input("please input your password:")
    if len(name.strip(' ')) != 0 or len(pwd.strip(' ')) != 0:
        if name == 'aaa' and pwd == '123456':
            print( "%s，欢迎登录，今天的日期是%s" % (name, datetime.date.today()) )
            break
        else:
            print( "账号或密码错误" )
    else:
        print( "用户名或密码不允许为空" )
else:
    print("失败次数太多")

 

结束后最后的提示是两条：

please input your name:1
please input your password:2
账号或密码错误
please input your name:1
please input your password:2
账号或密码错误
please input your name:1
please input your password:2
账号或密码错误
please input your name:1
please input your password:2
账号或密码错误
失败次数太多

账号或密码错误
失败次数太多

我想只显示最后的 “失败次数太多”

 

没有办法，只能增加判断了，如下：

#!/usr/bin/python
# -*-coding:utf-8 -*-
import datetime

for i in range(1,5):
    name = input("please input your name:")
    pwd = input("please input your password:")
    if i == 4:
        continue
    if len(name.strip(' ')) != 0 or len(pwd.strip(' ')) != 0:
        if name == 'aaa' and pwd == '123456':
            print( "%s，欢迎登录，今天的日期是%s" % (name, datetime.date.today()) )
            break
        else:
            print( "账号或密码错误" )
    else:
        print( "用户名或密码不允许为空" )
else:
    print("失败次数太多")

 

运行结果：

please input your name:1
please input your password:2
账号或密码错误
please input your name: 
please input your password: 
用户名或密码不允许为空
please input your name: 
please input your password: 
用户名或密码不允许为空
please input your name: 
please input your password: 
失败次数太多