【主要内容】
1. is 和 == 区别 id()函数 == 判断两边的值 is 判断内存地址回顾编码: 1. ASCII: 英文, 特殊字符, 数字, 8bit, 1byte 2. GBK: 中文 16bit, 2byte. 兼容ASCII 3. unicode: 万国码, 32bit 4byte. 兼容ASCII 4. UTF-8: 长度可变的unicode. 英文:8bit, 欧洲:１６bit, 中文:24bit 3byte python2 只能用ASCII python3 有unicode, 默认的编码就是unicode 内存里用的是unicode. 硬盘和网络传输用的是utf-8或者GBK2. encode() 编码. 获取到的是编码之后的结果. bytes3. decode() 解码. 把bytes编程我们熟悉的字符串
【代码】
1、is和==
1 # s = "alex 是 大 xx"
2 # abc = id(s) # 得到内存地址
3 # print(abc)
4
5 # lst = ["大阳哥", "佳琪哥", "小花生", "燃哥"]
6 # print(id(lst)) # 就是一个内存地址. 毫无意义
7
8
9 # lst = ["周杰伦", "燃哥"]
10 # lst1 = ["周杰伦", "燃哥"]
11 # print(id(lst))
12 # print(id(lst1))
13
14 # s = "燃哥"
15 # s1 = "燃哥"
16 # # 小数据池. 会对字符串进行缓存, 为了节省内存
17 # print(id(s))
18 # print(id(s1))
19
20 # tu = ("燃哥", "周杰伦")
21 # tu1 = ("燃哥", "周杰伦")
22 # print(id(tu), id(tu1))
23
24 # dic = {"a": "b", "c":"d"}
25 # dic1 = {"a": "b", "c":"d"}
26 # print(id(dic), id(dic1))
27
28 # a = 10
29 # b = 10
30 # print(id(a), id(b))
31
32 # 布尔也有,
33 # a = True
34 # b = True
35 # print(id(a), id(b))
36
37 # -5
38 # a = 257
39 # b = 257
40 # print(id(a), id(b))
41
42 # a = "小威"
43 # b = "小威"
44 # print(id(a), id(b))
45
46 # 1. id() 查看内存地址
47 # 2. str 有小数据池的
48
49 # == is id
50 # == 判断. 左右两端是否相等和一致, 比较的是内容
51 # is 判断. 判断的是内存地址 id()的值来判断 内存地址
52
53 # lst = ["马化腾", "小威"]
54 # lst2 = ["马化腾", "小威"]
55 # print(lst == lst2) # True
56 # print(lst is lst2) # False
57
58
59 # s = "alex"
60 # print("1111111111")
61 # print("1111111111")
62 # print("1111111111")
63 # print("1111111111")
64 # print("1111111111")
65 # print("1111111111")
66 # print("1111111111")
67 # print("1111111111")
68 # print("1111111111")
69 #
70 # s2 = "alex"
71 # print(s == s2) # True
72 # print(s is s2) # True. 小数据池
73
74 # s1 = "@akljflkasdjklfjkasdlfjklsdajfklsdajfklasdjkflasdjklfjsdaklfjsdakljfklasdjfklsdajfklsdajfklsdajklfsjadklfjsadklfjasdkljfklsdjfklsdjfklsdjfklsdjfklasdjfklasdjklfjasdklakljflkasdjklfjkasdlfjklsdajfklsdajfklasdjkflasdjklfjsdaklfjsdakljfklasdjfklsdajfklsdajfklsdajklfsjadklfjsadklfjasdkljfklsdjfklsdjfklsdjfklsdjfklasdjfklasdjklfjasdkl"
75 # s2 = "@akljflkasdjklfjkasdlfjklsdajfklsdajfklasdjkflasdjklfjsdaklfjsdakljfklasdjfklsdajfklsdajfklsdajklfsjadklfjsadklfjasdkljfklsdjfklsdjfklsdjfklsdjfklasdjfklasdjklfjasdklakljflkasdjklfjkasdlfjklsdajfklsdajfklasdjkflasdjklfjsdaklfjsdakljfklasdjfklsdajfklsdajfklsdajklfsjadklfjsadklfjasdkljfklsdjfklsdjfklsdjfklsdjfklasdjfklasdjklfjasdkl"
76 # print(id(s1), id(s2))
77 #
78 # s = "abc中def"
79 # print(s.title())
2、编码
1 # s = "alex马"
2 # 想要存储.必须进行编码
3
4 # encode() 编码之后的内容是bytes类型的数据
5
6 # 30个字节 10个字. 每个字3个字节
7 # b'\xe6\x9d\x8e\xe5\x98\x89\xe8\xaf\x9a\xe7\x9a\x84\xe5\x84\xbf\xe5\xad\x90\xe8\xa2\xab\xe7\xbb\x91\xe6\x9e\xb6\xe4\xba\x86'
8 # bs = s.encode("UTF-8") # 把字符串编码成UTF-8的形式
9 # print(bs)
10
11 # 英文:编码之后的结果是英文本身
12 # 中文:编码之后UTF-8 下. 一个中文3个字节
13
14
15 # s = "饿了么"
16 # bs = s.encode("GBK") # b'\xb6\xf6\xc1\xcb\xc3\xb4' GBK 一个中文:２个字节
17 # print(bs)
18
19 # s = "中"
20 # print(s.encode("utf-8"))
21 # print(s.encode("GBK"))
22
23 # decode()解码
24
25 # bs = b'\xb6\xf6\xc1\xcb\xc3\xb4' # 从别人那里读到的 GBK
26 #
27 # # 编程人认识的东西
28 # s = bs.decode("GBK") # 解码之后是字符串, 用什么编码就用什么解码
29 # print(s)
30
31 # GBK => utf-8
32 bs = b'\xb6\xf6\xc1\xcb\xc3\xb4'
33 # 先解码成unicode字符串
34 s = bs.decode("GBK")
35 # 在把字符串编码成UTF-8
36 bss = s.encode("UTF-8")
37 print(bss)
3、作业与练习
1 '''
2
3 s = "k:1|k1:2|k2:3|k3:4"
4 lst=s.split("|")
5 dic={}
6 for i in lst:
7 k,v = i.split(":")
8 dic[k]=int(v)
9 print(dic)
10
11 # 有如下值li=[11,22,33,44,55,66,77,88,99,90]
12 # 将所有大于66的值保存至字典的第一个key中，将小于66的所有值保存到第二个key值中
13 li=[11,22,33,44,55,66,77,88,99,90]
14 #法一
15 # dic={"k1":[],"k2":[]}
16 # for el in li:
17 # if el > 66:
18 # dic["k1"].append(el)
19 # elif el < 66:
20 # dic["k2"].append(el)
21 # else:
22 # pass
23 # print(dic)
24 dic={}
25 for el in li:
26 if el > 66:
27 dic.setdefault("k1",[]).append(el)
28 elif el < 66:
29 dic.setdefault("k2",[]).append(el)
30 print(dic)
31 '''
来源：https://www.cnblogs.com/fengxb1213/p/12290648.html