


In fact, strings are also a data type. However, what is special about strings is that there is an encoding problem. The following article mainly introduces you to the relevant information on string operations and encoding Unicode in Python. Friends in need can refer to it. Let’s take a look together.
This article mainly introduces you to some knowledge about string operations and encoding Unicode in Python. I won’t say much below. Friends who need it can come and learn together.
String type
str
: Unicode string. Strings constructed using '' or r'' are all str, and single quotes can be replaced with double quotes or triple quotes. Regardless of how you specify it, there is no difference when it is stored internally in Python.
bytes
: Binary string. Since files in other formats such as jpg cannot be displayed using str, they are represented by bytes. Each byte of bytes is a number from 0 to 255. When printing, Python will display the part that can be expressed in ASCII as ASCII, which makes it easier to read. bytes supports almost all str methods except formatting, even including the re module
bytearray()
: Binary string that can be changed in place.
utf-8 encoding range
Number of bytes | Storage format | |
1 byte | 0xxxxxxx | |
2 bytes | 110xxxxx 10xxxxxx | ##0x0800~FFFF(2048 ~ 65535) |
1110xxxx 10xxxxxx 10xxxxxx | ##0x10000~1FFFFFF(65536 ~ 2097152) | |
11110xxx 10xxxxxx 10xxxxxx 10xxxxxx | ##0x2000000~0x3FFFFFF | 5 bytes |
0x4000000~0x7FFFFFFF) | 6 bytes | |
Byte order mark BOM |
BOM is the abbreviation of byte order marker,
Specifies the rules when encoding is written
Using 'utf-16-be' will not write a BOM header, but using 'utf-16' will write a BOM header.
>>> open('h.txt','w',encoding='utf-8-sig').write('aaa') 3 >>> open('h.txt','rb').read() b'\xef\xbb\xbfaaa' >>> open('h.txt','w',encoding='utf-16').write('bbb') 3 >>> open('h.txt','rb').read() b'\xff\xfeb\x00b\x00b\x00' >>> open('hh.txt','w',encoding='utf-16-be').write('ccc') 3 >>> open('hh.txt','rb').read() b'\x00c\x00c\x00c' >>> open('h.txt','w',encoding='utf-8').write('ddd') 3 >>> open('h.txt','rb').read() b'ddd'
Rules when reading
If the correct encoding is specified, the BOM will be ignored, otherwise the BOM It will be displayed as garbled characters or an exception will be returned.>>> open('h.txt','r').read() '锘縟dd' >>> open('h.txt','r',encoding='utf-8-sig').read() 'ddd'
Encoding and decoding
chr and ord
>>> ord('中') #20013 >>> chr(20013) #'中'
- '\xhh': Use 2-digit hexadecimal to represent a character '\uhhhh': Use 4-digit hexadecimal to represent a character Represent a character:
'\Uhhhhhhhh': Use 8-digit hexadecimal to represent a character
str and bytes, bytearray conversion
str.encode( encoding='utf-8')
bytes(s,encoding='utf-8')<br>
bytes.decode(encoding='utf-8')<br>
str(B, encoding='utf-8')<br>
bytearray(string, encoding='utf-8')
bytearray(bytes)
Document encoding statement
Python uses utf-8 encoding by default.
: Indicates that the declaration document is latin-1 encoding.
Help function
sys.platform #'win32'
sys.getdefaultencoding() # 'utf-8'
sys.byteorder #'little'
s.isalnum() #s表示字符串
s.isalpha()
s.isdecimal
s.isdigit()
s.isnumeric()
s.isprintable()
s.isspace()
s.isidentifier() #如果字符串可以用作变量名,那么返回True
s.islower()
s.isupper()
s.istitle()

Python and C each have their own advantages, and the choice should be based on project requirements. 1) Python is suitable for rapid development and data processing due to its concise syntax and dynamic typing. 2)C is suitable for high performance and system programming due to its static typing and manual memory management.

Choosing Python or C depends on project requirements: 1) If you need rapid development, data processing and prototype design, choose Python; 2) If you need high performance, low latency and close hardware control, choose C.

By investing 2 hours of Python learning every day, you can effectively improve your programming skills. 1. Learn new knowledge: read documents or watch tutorials. 2. Practice: Write code and complete exercises. 3. Review: Consolidate the content you have learned. 4. Project practice: Apply what you have learned in actual projects. Such a structured learning plan can help you systematically master Python and achieve career goals.

Methods to learn Python efficiently within two hours include: 1. Review the basic knowledge and ensure that you are familiar with Python installation and basic syntax; 2. Understand the core concepts of Python, such as variables, lists, functions, etc.; 3. Master basic and advanced usage by using examples; 4. Learn common errors and debugging techniques; 5. Apply performance optimization and best practices, such as using list comprehensions and following the PEP8 style guide.

Python is suitable for beginners and data science, and C is suitable for system programming and game development. 1. Python is simple and easy to use, suitable for data science and web development. 2.C provides high performance and control, suitable for game development and system programming. The choice should be based on project needs and personal interests.

Python is more suitable for data science and rapid development, while C is more suitable for high performance and system programming. 1. Python syntax is concise and easy to learn, suitable for data processing and scientific computing. 2.C has complex syntax but excellent performance and is often used in game development and system programming.

It is feasible to invest two hours a day to learn Python. 1. Learn new knowledge: Learn new concepts in one hour, such as lists and dictionaries. 2. Practice and exercises: Use one hour to perform programming exercises, such as writing small programs. Through reasonable planning and perseverance, you can master the core concepts of Python in a short time.

Python is easier to learn and use, while C is more powerful but complex. 1. Python syntax is concise and suitable for beginners. Dynamic typing and automatic memory management make it easy to use, but may cause runtime errors. 2.C provides low-level control and advanced features, suitable for high-performance applications, but has a high learning threshold and requires manual memory and type safety management.


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