Getting to know the python version

1. Difference one:　　
   • python2x: The community is open to absorb the source code improvement functions of various great gods, resulting in non-standard source code, too much confusion and too much repetitive code .
   • python3x: Guido Van Rossum (the founder of Uncle Turtle) reorganized and standardized the source code in order to meet the goals of " elegance", "clearness" and "simpleness " .
2. Difference two:　　
   • python2x: The default encoding method ascii, the first line to display Chinese needs to be added: # -*- encoding: utf-8 -*- .
   • python3x: The default encoding is utf-8.
3. Difference three:　　
   • python2x: print 'content' print('content').
   • python3x: print('content').
4. Difference four:　　
   • python2x: raw_input(); input() is equivalent to eval().
   • python3x：input()。