When working with Python, it is important to know which version of the language you are using. This is especially crucial when dealing with code that is not compatible across different versions. In this article, we will explore three different ways to check if the code is written in Python 2.7 or Python 3 and above.

Option 1: Using the sys module

import sys

if sys.version_info[0] == 2:
    print("Python 2.7")
elif sys.version_info[0] == 3:
    print("Python 3 and above")
else:
    print("Unknown version")

The sys module provides access to some variables used or maintained by the interpreter and to functions that interact with the interpreter. By checking the value of sys.version_info[0], we can determine the major version of Python being used. If it is 2, we know it is Python 2.7. If it is 3, we know it is Python 3 and above. Any other value indicates an unknown version.

Option 2: Using the platform module

import platform

if platform.python_version_tuple()[0] == '2':
    print("Python 2.7")
elif platform.python_version_tuple()[0] == '3':
    print("Python 3 and above")
else:
    print("Unknown version")

The platform module provides an interface to various services that interact with the underlying platform. By using the python_version_tuple() function, we can obtain a tuple containing the major, minor, and micro version numbers of Python. We can then check the value of the first element to determine the major version.

Option 3: Using the sys.version variable

import sys

if '2.7' in sys.version:
    print("Python 2.7")
elif '3.' in sys.version:
    print("Python 3 and above")
else:
    print("Unknown version")

The sys.version variable contains a string that describes the version of Python. By checking if ‘2.7’ or ‘3.’ is present in the string, we can determine the major version. This approach is less precise than the previous options, as it relies on string matching.

After exploring these three options, it is clear that the first option using the sys module is the most reliable and recommended way to check the Python version. It provides a direct and accurate way to determine the major version of Python being used. The second option using the platform module is also a viable alternative. However, the third option using the sys.version variable is less reliable and should be avoided if possible.