variable, buffer value, encoding

variable, buffer value, encoding

--Tao Xin

Variable

declaring variables

eg

#!/usr/bin/env python

#-*-Coding:utf-8-*-

Name = "Daoxin"

The code above declares a variable named: Name, and the value of the variable name is: "Daoxin"

The role of a variable: a nickname that refers to what is stored in an address in memory

Rules for variable definitions:

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

• [' and ', ' as ', ' assert ', ' Break ', ' class ', ' Continue ', ' Def ', ' del ', ' elif ', ' Else ', ' except ', ' exec ', ' finally ', ' for ', ' F ' Rom ', ' Global ', ' if ', ' import ', ' in ', ' was ', ' lambda ', ' not ', ' or ', ' pass ', ' print ', ' raise ', ' return ', ' try ', ' while ', ' WI Th ', ' yield ']

C language, no strings, only characters, arrays

Hello---Five character (s)

Forge a string character array with a character array [' H ', ' e ', ' l ', ' l ', ' O ']

String attributes, once modified, re-created

Buffer

A certain buffer value in Python

eg

Define two variables I1 and I2

>>> i1=100

>>> i2=100

Input: ID (i1), ID (i2)

Output: (1501868224, 1501868224)

Assign value again

>>> i1=1

>>> i2=1

Input: ID (i1), ID (i2)

Output: (1501865056, 1501865056)

string, with buffer value, within a certain range, ID, over range, not the same, digital buffer value-5 to 257

Steps taken by Python file execution

Load Memory >>> Lexical analysis >>> parsing >>> compiling >>> bytecode >>> executing bytecode >>> machine code >>> Execute machine code

Coding

Ascii

(American Standard Code for Information interchange, United States Standards Information Interchange Code) is a Latin alphabet based computer coding system, mainly used to display modern English and other Western European languages, which can only be represented by a maximum of 8 bits (one byte) , that is: 2**8 = 256, so the ASCII code can only represent 256 symbols.

Unicode

Unicode (Uniform Code, universal Code, single code) is a character encoding used on a computer. Unicode is created to address the limitations of the traditional character encoding scheme, which sets a uniform and unique binary encoding for each character in each language, which specifies that characters and symbols are represented by at least 16 bits (2 bytes), that is: 2 **16 = 65536

UTF-8

UtF-8, which is compression and optimization of Unicode encoding, does not use a minimum of 2 bytes, but instead classifies all characters and symbols: the contents of the ASCII code are saved with 1 bytes, the characters in Europe are saved in 2 bytes, and the characters in East Asia are saved in 3 bytes ...

variable, buffer value, encoding