Getting started with python (must be able to start)

python Interpreter

• A compiled ： Compile source code into machine language （0101）, And save as binary file , The runtime computer runs the binaries directly （ benefits ： Fast execution , shortcoming ： Cross platform compatibility ,windows Executable documents ,Linux Unenforceable , Recompile every time you change the code ）【C Language ,Go Language 】
• interpreted ： Equivalent to an interpreter , Execute the source code directly , Translate while executing , While executing （ benefits ： Simple and clear , Good cross platform compatibility , As long as there is a compiler , shortcoming ： Inefficient execution ）【python,Java】
• notes ：Linux The default interpreter for is bash
• python Interpreter type ：
  1、 Cpython： The default is Cpython Interpreter , c Language implementation （ advantage ： official 、 Treasury ）
  2、 IPython： be based on CPython An interactive interpreter on top （ beautiful 、 Can be realized bash、shell compile ）
  3、Jpython：java Realization , Python The code will be converted into Java Bytecode
  4、IronPython：c# Realization
  5、PyPy：python Realized python Interpreter pypy High operational efficiency （ advantage ：JIT technology ： With cache function ： Compiled code , Don't recompile ）
  Interactive environment ： Type one line of code and execute one line of code （ Equivalent to wechat chat ）

python Prompt

>>>: type python The main prompt for the statement
···： Secondary prompt （ Add at the end of the line \ ： Line continuation operator ) Generally, it means that the statement does not end , No input completed

python Assignment

• Direct assignment ：a = 1 a = “ok”
• Continuous assignment ：a = b = 2
• Multiple assignment ：name,sex=‘zjh’,‘female’
• Assignment interchange ：a,b = b,a
  notes ： All code is copied from disk to memory for execution

python notes

Single-line comments ：#
Multiline comment ： Three pairs of （ single ） quotes
notes ：pycharm in ： Whole block comment ：ctrl+/

python Rule of grammar ：

Code segment ： Indent to distinguish code segments （ It is suggested that 4 Space to indent （pythonic））
Line break ： Carriage returns , At the end of the line, you can add ";"
Line continuation ： End of line “"
Write multiple statements on one line ： use ";" branch

see python edition ：python -V
see pip route ：pip -V
Installation tools ：pip install Library name （ipython）
( notes ： stay Linux The version and model shall be indicated ：python3 -V）

python Several built-in functions in

• id: View the memory address of the object （id(a) or print（id（a))
• help: View object help information
• dir: View the properties and methods of the object （dir(a): among center Usage method ：
  #print(name.center(20,"*"))# The length is 20,name In the middle , use * fill )
• type： View the type of object （int/str)

python One of the most popular IDE：pycharm

PyCharm Common shortcuts
• Ctrl + suspension / Click the left mouse button ： brief introduction / Enter code definition
• Ctrl + /： Line notes / Cancel line comment
• Ctrl + Shift + / ： Block annotation
• Ctrl + Alt + L ： Code formatting
• Ctrl + D ： Copy selected area or row
• Ctrl + R： Replace
• Shift+F10: function

User input ：input

pycharm Set the display format （ typeface 、 Background, etc ）
Set the code font size 、 Setting of line spacing
pycharm Background color 、 Font, etc
python script Setting template for , Declarable author 、 Creation time 、 file name 、IDE etc.