Does Python have a main() function?

Python does not have a built-in main() function like C++ or Java. However, it is common practice to use the if __name__ == "__main__": construct to define the entry point of a program.

When a script is run directly, the special variable __name__ takes the value "__main__". If the script is imported as a module into another script, __name__ will be equal to the module's name.

This allows executing certain code only when the script is run directly, such as running main functions, parsing command-line arguments, etc.

# my_module.py

def some_function():
    print("some_function executed")

if __name__ == "__main__":
    # This code runs only when my_module.py is executed directly
    print("Running script directly")
    some_function()

# script.py

import my_module

print("Importing my_module")
# This code runs when script.py is executed
# When imported, the if __name__ == "__main__": block in my_module.py does not execute
my_module.some_function()

When running my_module.py, the output will be:

Running script directly
some_function executed

When running script.py, the output will be:

Importing my_module
some_function executed