Forcing a python program to interpret using python 3

Question

I have python 2.7.6 and python 3.4 installed on windows 7 machine.

When I open command prompt for windows and type python, python 2.7.6 starts by default.

I have a python script which I want to compile (or interpret officially speaking) using python 3.4.

Is there a command to use python 3.4 from c:/ prompt? or make 3.4 the default python interpreter?

thanks

Answer 1

Recent versions of Python for Windows install a script called py that will do what you want.

You can either do py -3 script.py to explicitly tell the launcher that you want to use Python 3

or put something containing "python3" on the first line in a comment (ideally #!/usr/bin/env python3 for compatibility with other systems...) and just run script.py; the installer associates *.py files with the launcher, which in turn determines the version to run by looking at the first line of the script.

This mechanism is described in PEP 397.

Answer 2

To make sure that you are always running python 3, you can modify your Windows PATH Environment variable to include the python 3 directory, and remove the python 2 directory.