Python met

 Development:

Development Language:
    : 1. the Java level language Python, PHP C # C ++ ... Go Ruby     "bytecode ===
    : C, Assembler 2. low-level language                             machine code ==="

The contrast between languages:
   1 .PHP categories: for writing web pages, limitations
   2.Python Java: you can write on the page and can also write back-office functions
           ----- Python low efficiency, high development efficiency
          ----- Java implementation of high efficiency, development efficiency low

Python species:
   JPython
   IronPython 
   JavaScriptPython
   RubyPython
   CPython    
   ...
   PyPy       == "this is a CPython development Python

installation:
   Python installed on the OS, do: write a file written in accordance with the rules of python, the documents to Python contents of the software, read the document, and then convert and execute, get the final result.

   Python Software    ==> Python interpreter (Memory Management)
 
Download:
   A Python 3 continues to update
   Python2 continue to update

Window:
   python2
   python3 
   # environment variables
   with environment variables: configured according to their installation location.
        
Linux:
   python2
   to python3

attached:
win10 environment variable configuration:
         Method a: Use cmd command to add the path environment variable
                  input under cmd: path =% path%; D: \ Python27 then press "Enter" Enter key.   
                  Where: D: \ Python27 is Python installation directory.
         Method Two: Add the Python directory in the environment variable
                  (1) Right-click on "Computer" and then click "Properties"
                  (2) and then click on the "Advanced System Settings"
                  (3) Select "System Variables" window under the "Path", double-click you can!
                  (4) and then in the "Path" line, add the path to the python installation (my D: \ Python27). ps: Remember, the direct path with a semicolon ";" to separate!
                     
                 
                After (5) the last set successfully, the cmd command line, enter the command "