第二周第二节模块初识

块：别人写好的功能封装成一个名字，网上下载下来，导入后直接用，不用再写了
第三方库：下载下来安装上才能用
两个标准库：sys os
sys模块

import sys
print(sys.path) //打印环境变量

"C:Usersgoogle WANGAppDataLocalProgramsPythonPython36python.exe" D:/projects/sys.py
['D:\projects', 'D:\projects', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\python36.zip', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\DLLs', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\lib', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\lib\site-packages', 'C:\Program Files\JetBrains\PyCharm 2018.3.5\helpers\pycharm_matplotlib_backend']

Process finished with exit code 0

"C:Usersgoogle WANGAppDataLocalProgramsPythonPython36python.exe" D:/projects/sys_mode.py
['D:\projects', 'D:\projects', 'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\python36.zip',
'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\DLLs',
'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\lib', 、//一般标准库放在这里面
'C:\Users\google WANG\AppData\Local\Programs\Python\Python36',
'C:\Users\google WANG\AppData\Local\Programs\Python\Python36\lib\site-packages', //自己装的放在这里面
'C:\Program Files\JetBrains\PyCharm 2018.3.5\helpers\pycharm_matplotlib_backend']

Process finished with exit code 0
系统有环境变量
prthon也有环境变量

打印脚本的绝对路径，因为pycharm就是绝对路径，所以打印的是绝对路径

import sys
print(sys.argv)
输出结果：
"C:Usersgoogle WANGAppDataLocalProgramsPythonPython36python.exe" D:/projects/sys_mode.py
['D:/projects/sys_mode.py']

windows下dir是查看路径的

import os
os.system ("dir") //直接输出到屏幕上

 

"C:Usersgoogle WANGAppDataLocalProgramsPythonPython36python.exe" D:/projects/sys_mode.py
������ D �еľ��� �¼Ӿ�
������к��� A45A-FDF2

D:projects ��Ŀ¼

2019/04/08 19:06 <DIR> .
2019/04/08 19:06 <DIR> ..
2019/04/08 19:04 <DIR> .idea
2019/04/07 14:42 110 for+contiune.py
2019/04/07 14:16 42 Forѭ��.py
2019/04/07 14:22 308 forѭ����else.py
2019/04/07 14:49 123 forѭ��Ƕ��.py
2019/04/08 19:06 88 sys_mode.py
2019/04/07 11:08 197 test.py
2019/04/07 11:33 301 while+if else.py
2019/04/07 11:20 65 while.py
2019/04/07 11:35 273 while����if.py
2019/04/07 14:31 406 while������.py
2019/04/07 11:41 327 while�Դ�3����ʾ.py
11 ���ļ� 2,240 �ֽ�
3 ��Ŀ¼ 10,968,879,104 �����ֽ�

Process finished with exit code 0

import os
cmd_res=os.system ("dir") #执行命令，不保存结果
print("------->",cmd_res)

输出结果：
-------> 0 //0代表命令执行的状态码，0代表执行成功，非0代表错误

import os
cmd_res=os.popen ("dir") #执行命令，不保存结果
print("------->",cmd_res)

输出结果：-------> <os._wrap_close object at 0x000001F93B0DC898> 打印的内存对象的值

import os
cmd_res=os.popen ("dir").read() #后面加read就把结果读出来了
print("------->",cmd_res)
输出结果：


-------> 驱动器 D 中的卷是 新加卷
卷的序列号是 A45A-FDF2

D:projects 的目录

2019/04/08 19:16 <DIR> .
2019/04/08 19:16 <DIR> ..
2019/04/08 19:15 <DIR> .idea
2019/04/07 14:42 110 for+contiune.py
2019/04/07 14:16 42 For循环.py
2019/04/07 14:22 308 for循环加else.py
2019/04/07 14:49 123 for循环嵌套.py
2019/04/08 19:16 207 sys_mode.py
2019/04/07 11:08 197 test.py
2019/04/07 11:33 301 while+if else.py
2019/04/07 11:20 65 while.py
2019/04/07 11:35 273 while不加if.py
2019/04/07 14:31 406 while任意玩.py
2019/04/07 11:41 327 while试错3次提示.py
11 个文件 2,359 字节
3 个目录 10,969,739,264 可用字节

import os
cmd_res=os.popen ("dir").read()
print("------->",cmd_res)
os.mkdir("new_dir") //执行后创建一个新的目录