Variable, buffer value, encoding, Variable Buffer value Encoding

Variable, buffer value, encoding, Variable Buffer value Encoding
Variable, buffer value, encoding

-- Daoxin

Variable

Declare Variables

Eg:

#! /Usr/bin/env python

#-*-Coding: UTF-8 -*-

Name = "DaoXin"

The code above declares a variable named: name. The value of the variable name is: "DaoXin"

The role of a variable: nickname, which represents the content stored in an address in the memory.

Rule for variable definition:

• Variable names can only be any combination of letters, numbers, or underscores
• The first character of the variable name cannot be a number.
• The following keywords cannot be declared as variable names

• ['And', 'as', 'assert ', 'Break', 'class', 'contine', 'def', 'del ', 'elif ', 'else', 'Got t', 'exec ', 'Finally', 'for ', 'from', 'global', 'if', 'import', 'in ', 'Is ', 'lambda', 'not ',' or ', 'pass', 'print', 'raise ', 'Return', 'try', 'while ', 'with', 'yield ']

C language, no string, only characters, Arrays

Hello --- five characters

Use a character array to forge string character arrays ['h', 'E', 'l', 'l', 'O']

Character string feature. Once modified, re-create

Buffer

Buffer value in python

Eg:

Define two variables i1 and i2

>>> I1 = 100

>>> I2 = 100

Input: id (i1), id (i2)

Output: (1501868224,150 1868133)

Assign another value

>>> I1 = 1

>>> I2 = 1

Input: id (i1), id (i2)

Output: (1501865056,150 18.056)

String, With a buffer value, within a certain range, the id is the same, beyond the range, different, number buffer value-5 to 257

Python File Execution steps

Load memory> lexical analysis> syntax analysis> compile> bytecode> execute bytecode> machine code> execute machine code

Encoding

ASCII

American Standard Code for Information Interchange (American Standard Information Exchange Code) is a computer coding system based on Latin letters. It is mainly used to display modern English and other Western European languages, it can only be expressed in 8 bits (one byte) at most, that is, 2 ** 8 = 256. Therefore, the ASCII code can only represent 256 symbols at most.

Unicode

Unicode (unified code, universal code, Single Code) is a character encoding used on a computer. Unicode is generated to address the limitations of traditional character encoding schemes. It sets a uniform and unique binary encoding for each character in each language, it is specified that some characters and symbols are represented by at least 16 bits (2 bytes), that is, 2*16 = 65536

UTF-8

UtF-8 is the compression and optimization of Unicode encoding, which no longer uses at least 2 bytes, but classifies all characters and symbols: the content in the ascii code is saved in 1 byte, the European characters are saved in 2 bytes, and the East Asian characters are saved in 3 bytes...