Python Study (1) - Introduce Python

 

Why do I study Python  
    
      Each program has advantage itself, why I study python program? This book(*1)
      give us several  advantages :

      1   Software quality : Python script is designed to be readable , reusable and
           maintainable.

      2   Developer productivity : We don't need to complie program.

      3.  Program portability :  It is portable and  run on any operating  system
      4.  Module :  many module is written in python

      5.  Easy : Easy to learn, easy to read, easy to maintain

User 
     Many companys adopt Python language to develop its products. such as :google,
      youtube, dropbox, google app engine...etc

What do python do          
         1. GUI 
         2. OS program
         3. Internet program
         4. Component Integration
         5, Database program

Python feature       
         1. Dynamic typing : you don't need to declare a type or variable size in advance.
            Such as:  i = 0 ;
         2. Automatic memory management :  it   when the object is created
it can automatic create  and destroy
              object. python
         3. third-party utilities : developers  contribute many packages that is write in
             Python. To use these  save  your development time.
         4. easy to use : like human  syntax and simple read or write.
         5. free  :  It is free.

Download python             
              Download python install : https://www.python.org/downloads/
               Python 2.X  : it is a legacy.
               Python 3.X  : it is a evolution software and new features. such as: Unicode support.
               which version should I use : ref https://wiki.python.org/moin/Python2orPython3
             

       
    install

    Execute Python

 

 Python script execute          
           When the python code(.py) is executed first time, it will be into bytecode(.pyc).
            Bytecode is an implementation detail of the CPython interprete and low-level code.
            Bytecode makes execute faster than original source .
       

Python Virtual Machine(PVM)                  
         Python code is compiled to byte code(.pyc), PVM will execute the byte code.
          PVM is a engin of Python.

• Setting variable environment

1. Set your python environment variable
     
        Edit Path : C:\Python27\; C:\Python27\Scripts

    

     > python

 
    > ctrl + Z

  
    If you had installed many python versions, you can py -2 or  py -3 to switch   
     different  python version.

 

 Use IDLE
     1. Select IDLE , open Python Shell window    

 

      2. Execute python code
     

     3. To write python's script
    open New File.

    write a program

    Run Module or F5

    The script has executed and right to get answer

 

     

  
   

   
       
Note:
       *1. Learning Python, 5th Edition, O'Reilly Media, ISBN:978-1-44935-573-9