>>> import os
>>> os.getcwd()      # Return the current working directory
'C:\\Python315'
>>> os.chdir('/server/accesslogs')   # Change current working directory
>>> os.system('mkdir today')   # Run the command mkdir in the system shell
0

>>> import os
>>> dir(os)
<returns a list of all module functions>
>>> help(os)
<returns an extensive manual page created from the module's docstrings>

>>> import shutil
>>> shutil.copyfile('data.db', 'archive.db')
'archive.db'
>>> shutil.move('/build/executables', 'installdir')
'installdir'

>>> import glob
>>> glob.glob('*.py')
['primes.py', 'random.py', 'quote.py']

# demo.py 檔案
import sys
print(sys.argv)

['demo.py', 'one', 'two', 'three']

import argparse

parser = argparse.ArgumentParser(
    prog='top',
    description='Show top lines from each file')
parser.add_argument('filenames', nargs='+')
parser.add_argument('-l', '--lines', type=int, default=10)
args = parser.parse_args()
print(args)

>>> sys.stderr.write('Warning, log file not found starting a new one\n')
Warning, log file not found starting a new one

>>> import re
>>> re.findall(r'\bf[a-z]*', 'which foot or hand fell fastest')
['foot', 'fell', 'fastest']
>>> re.sub(r'(\b[a-z]+) \1', r'\1', 'cat in the the hat')
'cat in the hat'

>>> 'tea for too'.replace('too', 'two')
'tea for two'

>>> import math
>>> math.cos(math.pi / 4)
0.70710678118654757
>>> math.log(1024, 2)
10.0

>>> import random
>>> random.choice(['apple', 'pear', 'banana'])
'apple'
>>> random.sample(range(100), 10)   # 不重複抽樣
[30, 83, 16, 4, 8, 81, 41, 50, 18, 33]
>>> random.random()    # 區間 [0.0, 1.0) 中的隨機浮點數
0.17970987693706186
>>> random.randrange(6)    # 從 range(6) 中隨機選擇整數
4

>>> import statistics
>>> data = [2.75, 1.75, 1.25, 0.25, 0.5, 1.25, 3.5]
>>> statistics.mean(data)
1.6071428571428572
>>> statistics.median(data)
1.25
>>> statistics.variance(data)
1.3720238095238095

>>> from urllib.request import urlopen
>>> with urlopen('https://docs.python.org/3/') as response:
...     for line in response:
...         line = line.decode()             # 將 bytes 轉換為 str
...         if 'updated' in line:
...             print(line.rstrip())         # 移除最後面的換行符號
...
      Last updated on Nov 11, 2025 (20:11 UTC).

>>> import smtplib
>>> server = smtplib.SMTP('localhost')
>>> server.sendmail('[email protected]', '[email protected]',
... """To: [email protected]
... From: [email protected]
...
... Beware the Ides of March.
... """)
>>> server.quit()

>>> # 能夠輕易建立與格式化
>>> import datetime as dt
>>> now = dt.date.today()
>>> now
datetime.date(2003, 12, 2)
>>> now.strftime("%m-%d-%y. %d %b %Y is a %A on the %d day of %B.")
'12-02-03. 02 Dec 2003 is a Tuesday on the 02 day of December.'

>>> # 支援運算
>>> birthday = dt.date(1964, 7, 31)
>>> age = now - birthday
>>> age.days
14368

>>> import zlib
>>> s = b'witch which has which witches wrist watch'
>>> len(s)
41
>>> t = zlib.compress(s)
>>> len(t)
37
>>> zlib.decompress(t)
b'witch which has which witches wrist watch'
>>> zlib.crc32(s)
226805979

>>> from timeit import Timer
>>> Timer('t=a; a=b; b=t', 'a=1; b=2').timeit()
0.57535828626024577
>>> Timer('a,b = b,a', 'a=1; b=2').timeit()
0.54962537085770791

def average(values):
    """計算數字串列的算術平均數。

    >>> print(average([20, 30, 70]))
    40.0
    """
    return sum(values) / len(values)

import doctest
doctest.testmod()   # 自動驗證內嵌的測試

import unittest

class TestStatisticalFunctions(unittest.TestCase):

    def test_average(self):
        self.assertEqual(average([20, 30, 70]), 40.0)
        self.assertEqual(round(average([1, 5, 7]), 1), 4.3)
        with self.assertRaises(ZeroDivisionError):
            average([])
        with self.assertRaises(TypeError):
            average(20, 30, 70)

unittest.main()  # 從命令列呼叫會執行所有測試