一、学习的内容
1、命令 sys.path()
显示当前环境变量
2、命令os.system("dir")
显示当前目录内的文件，只显示，不保存结果
3、命令text = os.popen("dir").read()
显示当前目录内的文件，可保存结果
4、命令 os.mkdir("new_dir")
创建一个叫“new_dir”的文件夹
5、三元运算
a,b,c = 1,2,3
d = a if a> b else c
结果d =c
6、数据类型转换
字符串转二进制
‘你好’.encode("utf=8")
二进制转字符串
‘\xe4\xbd\xa0\xe5\xa5\xbd‘.decode("utf-8")
7、数组
name = [“aaa”,"bbb","ccc"]
print(name[0,2])，就是显示，aaa,bbb
print(name[-1])，就是显示，ccc
print(name[-2,-1])，就是显示，bbb,ccc
print(name[:3])，就是显示，aaa,bbb,ccc
name.append("444")，在最后插入
name.insert(1,"555")，插入到1
name.clear()，清空
name.reverse()，反转排序
name.sort()，按字母排序
name.remove("aaa")，删除aaa
name.delete[0]，删除0
name.extene([1,2,3,4])，添加数组
name2 = name.copy()，复制，不是引用，比如多层数组，对多层数组只COPY内存地址（指针），要导入 import copy
数组复制的其他写法 name2 = name[:] name2 = list(name)
name2 = name.deepcopy()，深层复制，也能完全复制多层数组
作业：
1、让用户输入工资
2、根据编号购买商品
3、选择商品后，看余额是否购，够就扣钱，不够重选
4、按Q退出，并打出购买过的商品和余额
1 product_list = [
2 (‘Iphone‘,5800),
3 (‘Mac Pro‘,9800),
4 (‘Bike‘,800),
5 (‘Watch‘,10600),
6 (‘Coffee‘,31),
7 (‘Alex Python‘,120),
8 ]
9 shoping_list = []
10 gongzi = input("输入工资")
11 if gongzi.isdigit(): #判断是否为数字
12 gongzi = int(gongzi)
13 for index,i in enumerate(product_list): #输出数组位置
14 print(index,i)
15 while True:
16 shangpings = input("输入要购买商品")
17 if shangpings.isdigit():
18 shangpings = int(shangpings)
19 if shangpings < 6 and shangpings >= 0:
20 aa = product_list[shangpings]
21 if aa[1] <= gongzi:
22 gongzi -= aa[1]
23 print("购买的商品是%s,余额是%s"%(aa[0],gongzi))
24 shoping_list.append(aa)
25
26
27 else:
28 print("余额不足，只有:",gongzi)
29 else:
30 print("输入错误")
31 elif shangpings == "q":
32 print("-----购买的商品列表------")
33 print(shoping_list)
34 print("余额:", gongzi)
35 exit()
36 else:
37 print("需要输入数字")
字符串操作
1 name.capitalize() 首字母大写
2 name.casefold() 大写全部变小写
3 name.center(50,"-") 输出 ‘---------------------Alex Li----------------------‘
4 name.count(‘lex‘) 统计 lex出现次数
5 name.encode() 将字符串编码成bytes格式
6 name.endswith("Li") 判断字符串是否以 Li结尾
7 "Alex\tLi".expandtabs(10) 输出‘Alex Li‘， 将\t转换成多长的空格
8 name.find(‘A‘) 查找A,找到返回其索引， 找不到返回-1
9
10 format :
11 >>> msg = "my name is {}, and age is {}"
12 >>> msg.format("alex",22)
13 ‘my name is alex, and age is 22‘
14 >>> msg = "my name is {1}, and age is {0}"
15 >>> msg.format("alex",22)
16 ‘my name is 22, and age is alex‘
17 >>> msg = "my name is {name}, and age is {age}"
18 >>> msg.format(age=22,name="ale")
19 ‘my name is ale, and age is 22‘
20 format_map
21 >>> msg.format_map({‘name‘:‘alex‘,‘age‘:22})
22 ‘my name is alex, and age is 22‘
23
24
25 msg.index(‘a‘) 返回a所在字符串的索引
26 ‘9aA‘.isalnum() True
27
28 ‘9‘.isdigit() 是否整数
29 name.isnumeric
30 name.isprintable
31 name.isspace
32 name.istitle
33 name.isupper
34 "|".join([‘alex‘,‘jack‘,‘rain‘])
35 ‘alex|jack|rain‘
36
37
38 maketrans
39 >>> intab = "aeiou" #This is the string having actual characters.
40 >>> outtab = "12345" #This is the string having corresponding mapping character
41 >>> trantab = str.maketrans(intab, outtab)
42 >>>
43 >>> str = "this is string example....wow!!!"
44 >>> str.translate(trantab)
45 ‘th3s 3s str3ng 2x1mpl2....w4w!!!‘
46
47 msg.partition(‘is‘) 输出 (‘my name ‘, ‘is‘, ‘ {name}, and age is {age}‘)
48
49 >>> "alex li, chinese name is lijie".replace("li","LI",1)
50 ‘alex LI, chinese name is lijie‘
51
52 msg.swapcase 大小写互换
53
54
55 >>> msg.zfill(40)
56 ‘00000my name is {name}, and age is {age}‘
57
58
59
60 >>> n4.ljust(40,"-")
61 ‘Hello 2orld-----------------------------‘
62 >>> n4.rjust(40,"-")
63 ‘-----------------------------Hello 2orld‘
64
65
66 >>> b="ddefdsdff_哈哈"
67 >>> b.isidentifier() #检测一段字符串可否被当作标志符，即是否符合变量命名规则
68 True