In Windows, the python 2.x interpreter and the 3.x interpreter coexist.

In Windows, the python 2.x interpreter and the 3.x interpreter coexist.

Python2 and Python3 are incompatible. If you encounter a situation where you cannot upgrade to Python2 code or your colleagues stick to the Python2 camp, you must consider the coexistence of Python2 and Python3 in the system.

Mac OS X and Linux do not have to consider this situation. Because these Unix-like operating systems will directly map to Python3 when installing Python3. Install Python 2 and Python 3 at the same time.

Here we will only discuss Windows. Below are my common methods.

1. Create a D: \ Python folder;

2. Install Python 2.7 to D: \ Python27 and install Python 3.4 to D: \ Python34. Do not add Python to the path environment variable during installation;

3. create d: \ Python \ py2.bat with the following content:

D: \ Python \ 27 \ python.exe % *

4. create d: \ Python \ py3.bat with the following content:

D: \ Python \ 34 \ python.exe % *

5. Add D: \ Python to the environment variable PATH.

After such processing, you can directly input

Py3 yourpythonfile. py arg1 arg2

And Python2.