作业：
'''
1.让用户输入用户名与密码
2.校验用户名是否存在
3.用户名存在后检验密码是否正确，若正确打印“登陆成功”
否则打印“用户名或密码错误”，并让用户重新输入
4.用户密码输入错误超过三次则退出循环。
'''
def login():
i = 1
while i <= 3:
user = input('请输入用户名：').strip()
pwd = input('请输入密码：').strip()
with open('user.txt', 'r', encoding='utf-8') as f:
old_info = f.read().split(',')
for index in range(len(old_info)):
if old_info[index] == user:
if old_info[index+1] == pwd:
print("登录成功")
i = 4
break
else:
print("用户名或密码错误")
i += 1
break
login()
结果：
总结：
1.列表类型主要方法、深拷贝与浅拷贝：
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# 列表内置方法
list1
=
[
'hao'
,
20
,
'male'
,
2.0
,
3
,
'广东'
]
print
(list1[
4
])
print
(list1[
-
2
])
list1.append(
'张伟'
)
print
(list1)
list1.insert(
1
,
'li'
)
print
(list1)
list2
=
list1.copy()
print
(list2,
'添加值前'
)
list3
=
list1
print
(list3,
'添加值前'
)
list1.append(
'jie'
)
print
(list2,
'后'
)
print
(list3,
'后'
)
from
copy
import
deepcopy
list4
=
[
'hao'
,
20
,
'male'
,
2.0
,
3
,
'广东'
,[
12
,
3
]]
list6
=
deepcopy(list4)
list5
=
list4.copy()
list4[
6
].append(
4
)
print
(list4,
'前'
)
print
(list5,
'后'
)
print
(list6,
'后'
)<br><br>
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extend()
# 合并
list1
=
[
1
,
2
,
3
]
list2
=
[
4
,
5
,
6
]
list1.extend(list2)
print
(list1)
# 9.reverse() # 反转
list1.reverse()
print
(list1)
# 10.sort() # 排序
list3
=
[
1
,
3
,
5
,
8
,
10
,
2
,
4
,
6
]
# 升序
# list3.sort()
# print(list3)
# 降序
list3.sort(reverse
=
True
)
print
(list3)
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2.两种快捷建用法：
# tab : 往右空四个空格
# shift + tab : 往左减四个空格
3.字典及常用方法
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#字典常用方法--无序
#按照key取值
dict1
=
{
'name'
:
'hao'
,
'age'
:
20
,
'sex'
:
'male'
,
'school'
:
'ahpu'
}
print
(dict1[
'school'
])
print
(dict1.get(
'px'
))
print
(dict1.get(
'school'
,
'hnlg'
))
print
(dict1.get(
'san'
,
'1500'
))
#删除
# del dict1['name']
# print(dict1)
dict2
=
{
"position"
:
"student"
}
dict1.update(dict2)
print
(dict1)
#遍历
for
k,v
in
dict1.items():
print
((k,v))<br><br>
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#长度len
print
(
len
(dict1))
#成员运算in和not in
print
(
'name'
in
dict1)
print
(
'sal'
in
dict1)
print
(
'sal'
not
in
dict1)
#随机取出字典中的某个值
dict1.popitem()
print
(dict1)
#keys、values、items
print
(dict1.keys())
print
(dict1.values())
print
(dict1.items())
#循环
# 循环字典中所有的key
for
key
in
dict1:
print
(key)
# update()
print
(dict1)
dict2
=
{
"work"
:
"student"
}
# 把dict2加到dict1字典中
dict1.update(dict2)
print
(dict1)
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4.集合--一般用于去重
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# 在{}以逗号隔开，可存放多个值，但集合会自带默认去重功能。
set1
=
{
1
,
2
,
3
,
4
,
2
,
1
,
3
,
4
}
print
(set1)
# 集合是无序的
set1
=
set
()
set2
=
{}
print
(set1)
print
(set2)
set2[
'name'
]
=
'tank'
print
(
type
(set2))
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5.元组tuple
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# 二 元组类型(在小括号内，以逗号隔开存放多个值)
# 注意: 元组与列表的区别，元组是不可变类型，列表是可变类型。
tuple1
=
(
1
,
2
,
3
,
4
,
5
,
6
)
print
(tuple1)
# 1.按索引取值
print
(tuple1[
2
])
# 2.切片(顾头不顾尾)
print
(tuple1[
0
:
6
])
# (1, 2, 3, 4, 5, 6)
# 步长
print
(tuple1[
0
:
6
:
2
])
# (1, 3, 5)
# 3.长度
print
(
len
(tuple1))
# 6
# 4.成员运算 in 和 not in
print
(
1
in
tuple1)
# True
print
(
1
not
in
tuple1)
# False
# 5.循环
for
line
in
tuple1:
print
(line)
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6.文件操作
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# 文件读写基本使用
# 对文本进行操作
# open（参数1: 文件的绝对路径/文件的名字，参数2:操作模式， 参数3: 指定字符编码）
# f: 称之为 句柄
# r: 避免转义符
# 打开文件会产生两种资源，一种是python解释器与python文件的资源,程序结束python会自动回收。
# 另一种是操作系统打开文件的资源，文件打开后，操作系统并不会帮我们自动收回，所以需要手动回收资源。
# 写文件
f
=
open
(r
'E:\\pycharm2018\\PyCharm-Pro\\ya.txt'
,mode
=
"wt"
,encoding
=
"utf-8"
)
#默认模式rt
f.write(
"hello!"
)
f.close()
#读文件
f
=
open
(r
'E:\\pycharm2018\\PyCharm-Pro\\ya.txt'
,mode
=
"r"
,encoding
=
"utf-8"
)
res
=
f.read()
print
(res)
f.close()
#追加模式
f
=
open
(
file
=
r
'E:\\pycharm2018\\PyCharm-Pro\\ya.txt'
,mode
=
"a"
,encoding
=
"utf-8"
)
f.write(
"\nhigh"
)
f.close()
#with open方式
# 文件处理之上下文管理: with
# with会自带close()功能，
# 会在文件处理完以后自动调用close()关闭文件
with
open
(r
'E:\\pycharm2018\\PyCharm-Pro\\yh.txt'
,mode
=
"w"
,encoding
=
"utf-8"
) as f:
f.write(
"life is long"
)
with
open
(r
'E:\\pycharm2018\\PyCharm-Pro\\yh.txt'
,mode
=
"r"
,encoding
=
"utf-8"
) as f:
res
=
f.read()
print
(res)
with
open
(r
'E:\\pycharm2018\\PyCharm-Pro\\yh.txt'
,mode
=
"a"
,encoding
=
"utf-8"
) as f:
f.write(
' baidu'
)
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<br>
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7.图片与视频读写操作
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import
requests
res
=
requests.get(
'https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1560323359733&di=3e9865f9690a76e8db8279cb68834263&imgtype=0&src=http%3A%2F%2Fpic.rmb.bdstatic.com%2Fcd2476300bbad8dfcfff1d277b79401a.jpeg'
)
print
(res.content)
#写入图片
with
open
(
'风景.jpeg'
,
'wb'
) as f:
f.write(res.content)
#读取图片
with
open
(
'风景.jpeg'
,
'rb'
) as f:
res
=
f.read()
print
(res)
#文件拷贝操作
with
open
(
'风景.jpeg'
,
'rb'
) as f,
open
(
'风景2.jpeg'
,
'wb'
) as w:
res
=
f.read()
w.write(res)
#视频,一次打开
# with open('Eddy Kim - When A Long Night Comes (긴 밤이 오면).mkv.mkv','rb') as f,open('copy.mkv','wb') as w:
# res=f.read()
# print(res)
# w.write(res)
#一行一行打开，防溢出
with
open
(
'Eddy Kim - When A Long Night Comes (긴 밤이 오면).mkv.mkv'
,
'rb'
) as f,
open
(
'copy.mkv'
,
'wb'
) as w:
f.read()
for
line
in
f:
w.write(line)
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