Article directory
Foreword:
Python is the most popular programming language in the 21st century. There are various learning videos on the market in an endless stream, and the learning atmosphere about Python is gradually getting stronger! ! Recently, more and more friends have sent me private messages, hoping that I would publish a basic introduction to Python. After working hard for N hours, I finally compiled this "Essential Knowledge for Basic Introduction to Python"!
1. Identifier
Identifiers are names used in programming. They are used to name variables, functions, statement blocks, etc. In Python, identifiers are composed of letters, numbers, and underscores. They cannot start with numbers and are case-sensitive.
Identifiers starting with an underscore have special meanings. Identifiers starting with a single underscore, such as: _xxx, indicate class attributes that cannot be accessed directly. They need to be accessed through the interface provided by the class and cannot be imported with from xxx import *; identifiers starting with a double underscore Identifiers, such as: __xx, represent private members; identifiers starting and ending with double underscores, such as: xx , represent built-in identifiers in Python, such as: init () represents the constructor of a class.
2. Keywords
The above table is keywords (reserved words) in Python. We cannot use keywords when customizing identifiers.
3. Quotation marks
Python can use quotation marks ('), double quotation marks ("), and triple quotation marks (''' or """) to represent strings. The beginning and end of the quotation marks must be of the same type. Triple quotation marks can be composed of multiple lines. As follows:
id = '001'
name = "张三"
skill = '''
唱歌
跳舞'''
skill = """
唱歌
跳舞"""
4. Encoding
The default encoding in Python2 is ASCII. If the content is Chinese characters, it cannot be output and read correctly without specifying the encoding. For example, if we want to specify the encoding as UTF-8, in Python, we can add # at the beginning - - coding: UTF-8 - - Make the designation.
The default encoding in Python3 is UTF-8, so when using Python3, we usually do not need to specify the encoding.
5. Input and output
Python output uses print(), and the content is added in parentheses. As follows:
print('Hello Python')、
Python provides an input() that allows users to enter a string and store it in a variable. As follows:
name = input()
print('Hi',name)
6. Indentation
Python does not use {} to control classes, functions, logical judgments, etc., but uses indentation, and the indentation spaces are variable. As follows:
if True:
print(True)
else:
print(False)
7. Multiple lines
In Python, a new line is generally used as the end mark of a statement. You can use \ to divide a line of statements into multiple lines for display. As follows:
a = 128
b = 1024
c = 512
d = a + \
b - \
c
If enclosed in [], {}, () brackets, you do not need to use \. As follows:
arr = {
a,
b,
c
}
8. Comments
In Python, single-line comments use #, and multi-line comments use three single quotes (''') or three double quotes ("""). As shown below:
# 我是单行注释
'''
我是多行注释
我是多行注释
'''
"""
我是多行注释
我是多行注释
"""
9. Data type
- Integer : can be of any size, including negative numbers
- Floating point numbers : decimals
- String : text enclosed in single quotes ', double quotes ", triple quotes ''' or """
- Boolean : only two values: True and False
- Empty value : represented by None
- Variable : is mutable
- Constant : immutable
10. Operator
10.1 Common operators
10.2 Operator precedence
Base
Python basics (2): basic statements
Python basics (3): I am a number
Python Basics (4): Strings
Python Basics (5): Sequence
Python Basics (6): Lists and Tuples
Python Basics (7): Dictionaries and Collections
Python basics (8): time-related modules
Python Basics (9): Functions
Python Basics (10): Modules and Packages
Python Basics (11): Object Oriented
Python basics (12): basic file operations
Python basics (13): os module
Python Basics (14): Errors and Exceptions
Python Basics (15): Enumeration
Python Basics (16): Iterators and Generators
Python Basics (17): Decorators
Python Basics (18): Namespace & Scope
Python Basics (19): Mathematics-related modules
Python basics (20): sys module
Python basics (21): argparse module
Python basics (22): regular expressions
Advanced
Python Advanced (1): Multithreading
Python Advanced (2): Multi-process
Python Advanced (3): Sending and Receiving Emails
Python Advanced (4): MySQL for Database Operations
Python Advanced (5): SQLite for Database Operations
Python Advanced (6): Basic Excel Operations
Python Advanced (7): Basic Word Operations
Python Advanced (8): Basic XML Operations
Python Advanced (9): Basic JSON Operations
Python Advanced (10): Network Programming
reptile
100+ Python crawler classic practical projects
Python crawler (1): crawler disguise
Python crawler (2): Requests library
Python crawler (3): BeautifulSoup library
Python crawler (4): Selenium framework
Python crawler (5): PyQuery framework
Python crawler (6): Scrapy crawls scenic spot information
Python crawler (7): pyspider usage
Python crawls Zhihu Q&A
Python crawls public account articles
Python crawls the barrage of "Houlang" on station B
Python crawls iQiyi's "Republic of China" barrage
Use Python to crawl all skins of League of Legends (lol)
Python crawls comments on Douban's "The Party at Southern Station"
I used Python to crawl the comment areas of three major dating software, and the result...
Crawling the Weibo comments of Lin Dan and Zhao Yaqi to see what netizens said
automation
Word batch conversion to PDF
Python batch merge Excel
Automation artifact! Python batch reads ID card information and writes it to Excel
Just read this article to get started with Python + Appium automated WeChat operations.
Use Python to automatically grab red envelopes on WeChat. You no longer have to worry about not being able to grab red envelopes.
I used Python to find out all the people who deleted my WeChat and deleted them automatically.
Use Python to automatically collect energy from Ant Forest on a scheduled basis, so you no longer have to worry about forgetting to collect it.
data analysis
Python data analysis (1): basic knowledge of NumPy
Python data analysis (2): Matplotlib drawing
Python data analysis (3): First introduction to Pandas
Python Data Analysis (4): Pandas Advanced
The most complete NumPy tutorial
Python analysis of "Longling Mysterious Cave"
Python draws various epidemic maps
Python data analysis introductory knowledge manual
Pandas Cheat Sheet&Chinese Documentation&Video Tutorial
Use Python to analyze the movie "My Hometown and Me"
2022 Spring Festival movies are released, use Python to find out
Where did your friends hang out on National Day in 2021? Let Python tell you
wlh's melon is huge! I used Python to crawl the Guawen comment area and found it even more exciting.
Write mini games
mine clearance
Snake
tank battle
Airplane war
Happy Xiaoxiaole
Tetris
Plants vs. Zombies
Contra + 30 Python mini-games
Hobby Python
When Python meets WeChat
I fired my boss using Python
Use Python to write a Chinese Valentine's Day confession artifact
Use Python to implement WeChat automatic reply
Download Douyin videos without watermark using Python
Python implements the Matrix code rain effect
Use Python to create cool QR codes and analyze them
Write a beauty test gadget in Python
Send special Mother’s Day wishes using Python
Sao operation | Use Python to implement GIF reverse playback
Draw a funny (funny) expression using Python
Use Python to create an artistic signature gadget
I used Python to draw a plate of rice dumplings for everyone
Use Python to draw a Christmas tree with music on a snowy night
Prepare for 618, use Python to receive JD coupons
Use Python to implement the nine-square grid picture in the circle of friends
Use Python to implement an environmentally friendly and pollution-free fireworks show
Use Python to learn about the most dazzling Chinese comic "Five Elements of Wushan"
It’s almost Chinese New Year, I’ll use Python to write couplets & the character “福” for you
Face-changing function can be implemented in less than 100 lines of Python code
It was my friend’s birthday and I used Python to draw her a birthday cake.
Create beautiful ID photos with less than 20 lines of Python code
Use Python to generate "Happy May Day" from QQ friend avatars
One line of commands to put a mask on Fox Hunter F4 & detect whether it is wearing a mask
Use Python to add a small flag (small mooncake) to your avatar
Are you still worried about 520? Teach you how to write a confession artifact using Python
Documentation & Practical Projects
Python Learning Manual
Python3.10 official document PDF
100+ Python crawler classic practical projects
70 classic and practical Python practice projects (with source code)
Python interview guide PDF (245 Python interview questions)
240 Python practice cases with source code (seeing a hundred times is worse than practicing once)
Python self-study route
Python complete set of study notes (getting started + crawler + visualization & data analysis + machine learning + deep learning)
This complete version of the complete set of Python learning materials has been uploaded to CSDN. If you need it, friends can scan the CSDN official certification QR code below on WeChat to get it for free [ 保证100%免费]
