table of Contents

Introduction and use of built-in module

Introduction and use of built-in module

A, time module

Of the three forms of time Python:

Timestamp: to look at the computer
- From 1970-01-01 00:00:00 to the current time, in seconds calculation, calculate how many seconds
Formatting time (Format String): posters
- Returns the string time 2019-11-16
Time Object Format (struct_time):
- It returns a tuple, 9-tuple values:
  - They represent: year, month, day, hour, minute, second, day of the week, the first day of the year, daylight saving time

import time

Time stamp calculation used to obtain
print(time.time())
Acquisition time format, use format and save the user time splicing
- time.strftime('%Y-%m-%d %H:%M:%S')Minutes acquiring date
- % Y in
  % m dated
  % d day
  % H when
  % M minutes
  % S seconds

Gets the current time format

print(time.strftime('%Y-%m-%d'))    # 年月日
print(time.strftime('%H-%M-%S'))    # 时分秒

Gain practical objects

# 获取时间对象
print(time.localtime())
print(type(time.localtime()))
time_obj = time.localtime()
print(time_obj.tm_year)
print(time_obj.tm_hour)

res = time.localtime()
# 获取当前时间的格式化时间
print(time.strftime('%Y-%m-%d %H:%M:%S', time.localtime()))

# 将时间对象转为格式化时间
print(time.strftime('%Y-%m-%d %H:%M:%S', res))

# 将字符串格式的时间转化为时间对象
res = time.strptime('2019-01-01', '%Y-%m-%d')
print(res)

2019-11-16 15:23:17
2019-11-16 15:23:17
time.struct_time(tm_year=2019, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=1, tm_yday=1, tm_isdst=-1)

Two, datetime module

import datetime

# 获取当前年月日
print(datetime.date.today())

2019-11-16
# 获取当年年月日时分秒
print(datetime.datetime.today())

2019-11-16 15:26:37.224224

time_obj = datetime.datetime.today()
print(time_obj.year)
print(time_obj.month)
print(time_obj.day)

2019
11
16

# 从索引0开始计算周一
# UTC
print(time_obj.weekday())   # 0-6
# ISO
print(time_obj.isoweekday())    # 1-7

UTC time zone:

Beijing

print(datetime.datetime.now())

Greenwich

print(datetime.datetime.utcnow())

Calculating date / time

Date Date Time Time = "+" or "-" Time Object

Target = Date Time Time "+" or "-" Date Time

# 日期时间
current_time = datetime.datetime.now()
print(current_time)

# 获取7天时间
time_obj = datetime.timedelta(days=7)
print(time_obj)

# 获取当前时间 7天后的时间
later_time = current_time + time_obj
print(later_time)

time_new_obj = later_time - time_obj
print(time_new_obj)

Three, random module

import random

Obtaining a random arbitrary integer 1-9

res = random.randint(1, 9)
print(res)

Default get any decimals between 0-1

res1 = random.random()
print(res1)

The value of the iteration is performed in the object may be out of order (shuffling)

l1 = [5, 4, 9, 8, 6, 7, 3, 1, 2, 0]
random.shuffle(l1)
print(l1)

Gets a value may be a random iteration object

l1 = [5, 4, 9, 8, 6, 7, 3, 1, 2, 0]
print(random.choice(l1))

Exercise

Random codes

"""
需求:
    大小写字母、数字组合而成
    组合5位数的随机验证码
    
前置技术：
    chr() 可以将ASCII码表中值转换成对应的字符
"""

def get_code(n):
    code = ''
    for line in range(n):
        # 随机获取一个小写字母
        res1 = random.randint(97, 122)
        lower_str = chr(res1)

        # 随机获取一个大写字母
        res2 = random.randint(65, 90)
        upper_str = chr(res2)

        # 随机获取一个数字
        number = str(random.randint(0, 9))
        code_list = [lower_str, upper_str, number]
        random_code = random.choice(code_list)
        code += random_code

    return code

code = get_code(4)
print(code)

Four, OS module

import os

os is interacting with the operating system modules

Gets the parent directory of the current file

DAY15_PATH = os.path.dirname(__file__)
print(DAY15_PATH)
E:/python_file/day 15

The root directory of the project, the path associated values are in "constant"

BASE_PATH = os.path.dirname(DAY15_PATH)
print(BASE_PATH)
E:/python_file

Mosaic path: file splice "absolute path"

TEST_PATH = os.path.join(DAY15_PATH,'合集')
print(TEST_PATH)
E:/python_file/day 15\合集

Judgment "File / Folder" exists: If the file exists returns True, if there returns False

print(os.path.exists(TEST_PATH))
print(os.path.exists(DAY15_PATH))

False
True

Judgment "folder" exists

print(os.path.isdir(TEST_PATH))
print(os.path.isdir(DAY15_PATH))

False
True

Judgment "File" exists

print(os.path.isfile(TEST_PATH))
print(os.path.isfile(DAY15_PATH))

False
True

Create a folder

DIR_PATH = os.path.join(DAY15_PATH,'合集')
os.mkdir(DIR_PATH)

Delete the folder

os.rmdir(DIR_PATH)

Get the name of a folder, all files

# 获取某个文件夹下所有文件的名字，然后装进一个列表中
list1 = os.listdir('E:\python_file\day 15')
print(list1)
['01 time模块.py', '02 datetime模块.py', '03 random模块.py', '04 os模块.py', '05 sys模块.py', '06 hashlib模块.py', 'sys_test.py', 'test(day 15).py', '课堂笔记']

enumerate (iterables) ---> to give an object, the object has one tuple (index elements)

res = enumerate(list1)
print(list(res))

[(0, '01 time模块.py'), (1, '02 datetime模块.py'), (2, '03 random模块.py'), (3, '04 os模块.py'), (4, '05 sys模块.py'), (5, '06 hashlib模块.py'), (6, 'sys_test.py'), (7, 'test(day 15).py'), (8, '课堂笔记')]

Let the user select a file

list1 = os.listdir('E:\python_file\day 15')


res = enumerate(list1)
print(list(res))

# 让用户选择文件
while True:
    for index, file in enumerate(list1):
        print(f'编号{index} 文件名{file}')

    choice = input('请选择需要的文件编号：').strip()
    if not choice.isdigit():
        print('请输入数字')
        continue

    choice = int(choice)

    if choice not in range(len(list1)):
        print('编号范围出错')
        continue

    file_name = list1[choice]
    list1_path = os.path.join('E:\python_file\day 15', file_name)

    print(list1_path)
    with open(list1_path, 'r', encoding='utf-8')as f:
        print(f.read())

Five, sys module

import sys

Gets the path environment variable current Python interpreter

print(sys.path)

Add the environment variable to the current project

BASE_PATH = os.path.dirname(os.path.dirname(__file__))
sys.path.append(BASE_PATH)

Get cmd terminal command line Python py file in the user name and password

print(sys.argv)

Six, hashlib module

import hashlib

It is a cryptographic module hashlib

It built a lot of algorithms

MD5: algorithm undecipherable (2018)
Digest Algorithm
- The digest is encrypted string obtained from a content
- As a summary, it will be content as: guaranteed to be unique
- Ciphertext password is a summary

md5_obj = hashlib.md5()
print(type(md5_obj))
str1 = '1234'
# update中一定要传入bytes类型数据
md5_obj.update(str1.encode('utf-8'))

# 得到一个加密后的字符串
res = md5_obj.hexdigest()
print(res)

<class '_hashlib.HASH'>
81dc9bdb52d04dc20036dbd8313ed055

The above operation is likely to hit the library crack password true

To prevent the hit library problem: salt

def pwd_md5(pwd):
    md5_obj = hashlib.md5()
    str1 = pwd
    # update 中一定要传入bytes类型数据
    md5_obj.update(str1.encode('utf-8'))
    # 创造盐
    sal = '我套你猴子'
    # 加盐
    md5_obj.update(sal.encode('utf-8'))

    # 得到一个加密后的字符串
    res = md5_obj.hexdigest()
    return res

res = pwd_md5('1234')

user_str1 = f'yang:1234'
user_str2 = f'yang:{res}'

with open('user_info.txt', 'w', encoding='utf-8')as f:
    f.write(user_str2)

Analog user login feature

# 获取文件中的用户名密码
with open('user_info.txt', 'r', encoding='utf-8')as f:
    user_str = f.read()

file_user, file_pwd = user_str.split(':')

# 用户输入用户名和密码
username = input('请输入用户名：').strip()
password = input('请输入密码：').strip()

if username == file_user and file_pwd == pwd_md5(password):
    print('登录成功')
else:
    print('登录失败')