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if __name__ == "__main__" in Python

 


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if __name__ == "__main__" in Python

The if __name__ == "__main__" construct in Python is used to determine whether the Python script is being run as the main program or being imported as a module into another script. This is particularly useful for writing code that can be both imported and executed standalone.

1. Usage

The common usage of if __name__ == "__main__" is:


if __name__ == "__main__":
    # Code to be executed when the script is run directly

2. Example

Consider the following example:


# Module code
def hello():
    print("Hello, world!")

if __name__ == "__main__":
    # Executed when the script is run directly
    hello()

If you run this script directly, it will print Hello, world!. However, if you import this script as a module into another script, the hello() function will not be executed unless explicitly called.

3. Benefits

  • Allows a module to be both imported and run as a standalone script.
  • Helps separate code that is meant to be reusable from code that is meant to be executed directly.
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