What is the purpose of if __name__ == "__main__": in Python?
What is the purpose of if __name__ == "__main__": in Python?
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Updated 08 Apr 2025
The if
__name__=="__main__": line in Python controls the execution of script code based on direct execution or import usage as a module.Purpose
A Python file execution triggers the built-in variable __name__ with a specific value. When running a file directly, the built-in __name__ variable receives a value of "__main__". When a script functions as a module through import, then __name__ receives the module name, which excludes the
'.py'extension.The conditional block surrounding selected code blocks gives you a way to optimize runtime execution.
The code block executes only under conditions where the script runs directly instead of being loaded through other imports.
Why It’s Useful
Example
Running this file leads to displaying both lines; however, importing the file into another program provides access to greet() alone. Other files accessing this module will only receive the greet() function since the print statements remain unavailable for automatic execution. The approach for managing files using import is standard practice in Python platform development.