Python 2.0 =默认编码=ASSIC=不支持中文
Python 3.0 =默认编码=UNICODE=默认支持中文
In summary : Python 2.x is legacy, Python 3.x is the present and future of the language
总结：Python 2.x是遗产，Python 3.x 是现在和未来的语言。
Python 3.0 was released 发布 in 2008. The final 最终的 2.x version 2.7 release 发布 came out in mid-2010,
with a statement 声明 ofextended 延长 support 支持 for this end-of-life release.
The 2.x branch will see no new major releases after that. 3.x isunder active 活跃的 development 正在活跃的开发 and has already seen over five years of stable 稳定的 releases 版本 ,
including 包括 version 3.3 in 2012,3.4 in 2014, and 3.5 in 2015. This means that all recent 近期的 standard 标准的 library 库 improvements 升级/提升/改进, for example,
are only available 可用的 by default in Python 3.x.
Guido van Rossum (the original creator of the Python language) decided 决定 to clean up Python 2.x properly 适当的 ,
with less regard 不管 for backwards compatibility 兼容 向后兼容 than is the case for new releases in the 2.x range.
The most drastic 激进的 improvement is the better Unicode support 更好的中文支持 (with all text strings being Unicode by default) as well as saner bytes/Unicode separation.
Besides 除此之外 , several 几个 aspects 方面 of the core 核心 language (such as print and exec being statements,
integers using floor division) have been adjusted 调整为 to be easier for newcomers 新手 to learn and to be more consistent 持续的 with the rest of the language,
and old cruft has been removed (for example, all classes are now new-style, "range()" returns a memory efficient iterable, not a list as in 2.x).
Python 2 VS Python 3
1、默认支持中文
2、不兼容 2.0
3、核心语法调整易学
4、新特性默认只在3.x上有