python第二课

╰+哭是因爲堅強的太久メ 2022-06-01 06:45 353阅读 0赞

import sys  
print(sys.path)  \# 打印环境变量  
print(sys.argv\[2\])  \# 打印相对路径  
  
import os  
os.system("dir")  \# 执行命令，不保存结果  
cmd\_res = os.popen("dir").read()  
print("-->", cmd\_res)  
os.mkdir("new\_dir")  \# 创建当前路径目录

将写好的程序放入site-packages即可直接用其他程序调用。

.pyc 是什么？

python和java/c\#一样，也是一门基于虚拟机的语言。

当我们在命令行中输入python hello.py时，其实是激活了python的“解释器”，告诉“解释器”：你要开始工作了。

可是在“解释”之前，其实执行的第一项工作和java一样，是编译。我们在用eclipse之类的IDE时，将这两部给融合成了一部而已。其实python也一样，当我们执行python hello.py时，他也一样执行了这么一个过程，所以我们应该这样来描述python,python是一门先编译后解释的语言。

数据类型

1、数字

int(整型) long(长整型，python3里没这个类型)float(浮点型)complex(复数)

2、布尔值 1或0（真或假）

3、字符串

三元运算

a,b,c = 1,3,5

d = a if a >b else c

进制

二进制、八进制、十进制、十六进制

二转十六 取四合一，不够前部位整数，后补位小数。BH表示11，H表示16进制。或者0xB也表示16进制。

编码转换

msg = '我爱北京天安门'  
print(msg)  
print(msg.encode(encoding='utf-8').decode(encoding="utf-8"))

列表

names = \["ZhangYang", "Guyun", "ChenRonghua", "Xiangpeng", "XuLiangChen"\]  
print(names)  
print(names\[0\], names\[2\])  
print(names\[1:3\])  \# 切片  
print(names\[0:3\])  \# 切片  
print(names\[:3\])  \# 切片  
print(names\[-1\])  
print(names\[-3:-1\])  \# 切片  
print(names\[-3:\])  \# 切片  
names.append("LeiHaidong")  \# 插入  
names.insert(1, "ChenRonghua")  \# 插入  
names.insert(3, "Xinzhiyu")  \# 插入  
names\[2\] = "XieDi"  \# 修改  
names.remove("ChenRonghua")  \# 删除  
del names\[1\]  \# 删除  
names.pop()  \# 删除最后一个  
names.pop(0)  \# 删除第一个  
print(names.index("XieDi"))  \# index返回在列表的位置  
print(names\[names.index("XieDi")\])  
print(names.count("ChenRonghua"))  
names.clear()  \# 清空列表  
names.reverse()  \# 反转列表  
names.sort()  \# 排序 按照ASCII码的顺序来排  
  
names2 = \[1, 2, 3, 4\]  
names.extend(names2)  \# 合并列表  
  
import copy  
names = \["4ZhangYang", "\#!Guyun", "xXiangpeng", \["alex", "jack"\], "XuLiangChen"\]  
name2 = names.copy()  \# 复制列表仅仅复制第一层列表  
name3 = copy.deepcopy(names)  
names\[2\] = "向鹏"  
names\[3\]\[0\] = "ALEXANDER"  
print(names)  
print(name2)  
print(name3)  
  
for i in names:  \# 列表循环  
    print(i)  
  
print(names\[0:-1:2\])  \# 步长切片  
print(names\[::2\])     \# 步长切片

\#  创建联合账号

import copy  
person = \['name', \['saving', 100\]\]  
\# p1 = copy.copy(person)  
\# p2 = person\[:\]  
\# p3 = list(person)  
p1 = person\[:\]  
p2 = person\[:\]  
p1\[0\] = 'alex'  
p2\[0\] = 'fengjie'  
p1\[1\]\[1\] = 50  
names = ('alex', 'jack')  \# 元组

简单购物车程序

product\_list = \[  
    ('Iphone', 5800),  
    ('Mac Pro', 9800),  
    ('Bike', 800),  
    ('Watch', 10600),  
    ('Coffee', 31),  
    ('Alex Python', 120),  
\]  
shopping\_list = \[\]  
salary = input("Input your salary:")  
if salary.isdigit():  
    salary = int(salary)  
    while True:  
        for index, item in enumerate(product\_list):  
            \# print(product\_list.index(item), item)  
            print(index, item)  
        user\_choice = input("选择要买嘛？>>>:")  
        if user\_choice.isdigit():  
            user\_choice = int(user\_choice)  
            if user\_choice < len(product\_list) and user\_choice >= 0:  
                p\_item = product\_list\[user\_choice\]  
                if p\_item\[1\] <= salary:  \# 买得起  
                    shopping\_list.append(p\_item)  
                    salary -= p\_item\[1\]  
                    print("Adden %s into shopping cart, your current balance is \\033\[31;1m%s\\033\[0m" % (p\_item, salary))  
                else:  
                    print("\\033\[41;1m你的余额只剩\[%s\]啦，还买个毛线\\033\[0m" %salary)  
            else:  
                print("product code \[%s\] is not exist!" % user\_choice)  
        elif user\_choice == 'q':  
            print("----------shopping list----------")  
            for p in shopping\_list:  
                print(p)  
            print("Your current balance:", salary)  
            exit()  
        else:  
            print("invalid option")

字符串的操作

name = 'my \\tname is \{name\} and i am \{year\} old'  
print(name.capitalize())  
print(name.count("a"))  
print(name.center(50, "-"))  
print(name.endswith("ex"))  
print(name.expandtabs(tabsize=30))  
print(name\[name.find("name"):\])  \# 字符串可以切片  
print(name.format(name='alex', year=23))  
print(name.format\_map(\{'name': 'alex', 'year': 12\}))  
print('ab23'.isalnum())  \# 判断是不是阿拉伯数字和字母  
print('abA'.isalpha())  
print('1A'.isdecimal())  \# 判断十进制  
print('1A'.isdigit())  
print('a 1A'.isidentifier())  \# 判断是不是合法变量名  
print('33.33'.isnumeric())   \# 判断是不是纯数字  
print('My Name Is '.istitle())   \# 判断是不是空格  
print('My Name Is '.isprintable())  \# tty file ,drive file  
print('My Name Is '.isupper())  
print('+'.join(\['1', '2', '3', '4'\]))  
print(name.ljust(50, '\*'))  
print(name.rjust(50, '\*'))  
print('Alex'.lower())  
print('Alex'.upper())  
print('\\nAlex'.lstrip())  
print('Alex\\n'.rstrip())  
print('\\n  Alex\\n'.strip())  
p = str.maketrans("abcdef", '123456')  
print("alex li".translate(p))  
print('alex li'.replace('l', 'L', 1))  
print('alex li'.rfind("l"))  
print('1+2+3+4'.split("+"))  
print('1+2\\n+3+4'.splitlines())  
print('Alex Li'.swapcase())  
print('Alex Li'.title())  
print('Alex Li'.zfill(50))

字典

\# key-value  
info = \{  
    'stu1101': "TL",  
    'stu1102': "LZ",  
    'stu1103': "XZ",  
\}

info.update()

info.items()

c = dict.formkeys(\[6,7,8\],"A","B","C")

print(info.get('stu1103'))  
print('sut1103' in info)    
print(info)  
print(info\["stu1101"\])  
info\["stu1101"\] = "武"  
info\["stu1104"\] = "CJ"  
del info\["stu1101"\]  
info.pop("stu1101")  
info.popitem()  \# 随机删一个

info.values()  \#打印所有的值

info.keys()  \# 打印所有的key

for i in info:

print(i,info\[i\])

for k,v in info.items():

print(k,v)

多级菜单

data = \{  
    '北京': \{  
        "昌平": \{  
            "沙河": \["oldboy", "test"\],  
            "天通苑": \["链家地产", "我爱我家"\]  
        \},  
        "朝阳": \{  
            "望京": \["奔驰", "陌陌"\],  
            "国贸": \{"CICC", "HP"\},  
            "东直门": \{"Advent", "飞信"\},  
        \},  
        "海淀": \{\},  
    \},  
    "山东": \{  
        "德州": \{\},  
        "青岛": \{\},  
        "济南": \{\}  
    \},  
    "广东": \{  
        "东莞": \{\},  
        "常熟": \{\},  
        "佛山": \{\},  
    \},  
\}  
exit\_flag = False  
while not exit\_flag:  
    for i in data:  
        print(i)  
    choice = input("选择进入>>:")  
    if choice in data:  
        while not exit\_flag:  
            for i2 in data\[choice\]:  
                print("\\t", i2)  
            choice2 = input("选择进入>>:")  
            if choice2 in data\[choice\]:  
                while not exit\_flag:  
                    for i3 in data\[choice\]\[choice2\]:  
                        print("\\t\\t", i3)  
                    choice3 = input("选择进入>>:")  
                    if choice3 in data\[choice\]:  
                        for i4 in data\[choice\]\[choice2\]\[choice3\]:  
                            print("\\t\\t", i4)  
                        choice4 = input("最后一层，按b返回>>:")  
                        if choice4 == "b":  
                            pass  
                        elif choice4 == "q":  
                            exit\_flag = True  
                    if choice3 == "b":  
                        break  
                    elif choice3 == "q":  
                        exit\_flag = True  
            if choice2 == "b":  
                break  
            elif choice2 == "q":  
                exit\_flag = True