学习python最为纠结的是：网络上很多2.x的说明，但自己用的是python3.x，linux下通过软链接很轻松地就解决了这一问题，那么，windows下如何呢。

google了一下，在stackoverflow下找出了答案：

here is a better way of coexistence/launching of Python 2 and Python 3 on Windows. The Python 3.3 introduced the Python launcher for Windows (see http://www.python.org/dev/peps/pep-0397/).

After installation of Python 3.3, the py.exe and pyw.exe is copied to your c:\Windows directory, and the associations are set for the .py extension so that it uses the launcher. By default, Python 2 is launched for py script.py. The py -3 script.py launches Python 3. (This also means that no path for Python must be added to the environment -- the C:\Windows already is in the PATH.)

The best of all is that #!python2 in the script causes lauching via Python 2, the #!python3 causes launching the script via Python 3. This way, you can use scripts for both versions of Python, and you can lauch them the unified way -- py script.py or by just clicking on the script icon.

There are more details but this is basically what you need.

以上内容就是说，python3.3.msi安装时，会在c:/windows下放置 py.exe, pyw.exe这两个文件，你在cmd下输入，py就是python2.x的执行，py -3就调出了python3.x。

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