directory

  • A brief introduction.
    • 1.__name__
    • 2. ‘__main__’
    • 3. The __name__ = = “__main__”
  • Role.
  • Guess you like it

Recommended path for learning Python: Python Learning Directory >> Python Basics

Those of you who have studied C or Java probably know that programs run with a main entry. Python, on the other hand, can run a block of code from top to bottom even without a main entry. __name__ == “__main__” is still used in many Python open source projects or modules.

oneIntroduction to the

1.__name__

** __name__** is a Python built-in property and is a system global variable! Each py file has its own __name__ :

** If the py file is imported as a module, __name__ is the filename of the py file (also known as the module name); arunachal

** If the py file is run directly (Ctrl+Shift+F10), then __name__ defaults to the string “__main__”; arunachal

Take a simple example: suppose your name is Zhang SAN

In the eyes of friends, you are Zhang SAN (__name__ == ‘Zhang SAN ‘);

In your own eyes, you are yourself (__name__ == ‘__main__’)

2. ‘__main__’

‘_ _main_ _’ is actually onestring, used to identify program entry, not too many bells and whistles.

3.__name__ == ‘__main__‘* * * *

When the.py file is run directly (Ctrl+Shift+F10), the code block under ** if __name__ == ‘__main__’ will be run, which is equivalent to Python’s main function entry **, as shown in the following example:

A. Create a new my_name. Py file as a module file:

#! Usr /bin/env python # -* -coding :utf-8 _*- "" www.codersrc.com @file :Python __name__ == '__main__'. Py @time :2021/04/24 08:00 @motto: A thousand miles without a small stream without a river or sea. The wonderful program life needs to accumulate unremittingly! "" "# define a function and print the __name__ def prit_name () : print (" my_name. Py __name__ : ", __name__) if __name__ = = "__main__" : prit_name ()Copy the code

B. Create a python_main.py file and use it as the startup file (Ctrl+Shift+F10) :

#! Usr /bin/env python # -* -coding :utf-8 _*- "" www.codersrc.com @file :Python __name__ == '__main__'. Py @time :2021/04/24 08:00 @motto: A thousand miles without a small stream without a river or sea. The wonderful program life needs to accumulate unremittingly! # define a function and print __name__ def prit_name(): my_name.prit_name() print("python_main.py __name__:", __name__) if __name__ == "__main__": Prit_name () "' output: my_name. Py __name__ : my_name python_main. Py __name__ : __main__ ' ' 'Copy the code

Python_main. py is the boot file whose built-in attribute __name** is equal to ‘__main__’, and myname. py is the import module whose __name** is equal to the filename (also known as the module name). So the expression in my_name. Py if __name__ == ‘__main__’ does not hold! arunachal

When my_name.py is directly used as the startup file (Ctrl+Shift+F10), output:

my_name.py __name__: __main__
Copy the code

conclusion

If the py file is imported as a module, __name__ is the filename of the py file (also known as the module name);

If the py file is run directly (Ctrl+Shift+F10), then __name__ defaults to the string ‘__main__’ **; arunachal

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Role.

1.__name__ == ‘__main__’ as the main entry to start the py file;

2. A project will inevitably contain multiple module files, each module file after writing their own code will do some simple tests to detect bugs or write a simple example of their own function calls, and appropriately: __name__ == ‘__main__’ will not affect your test code, nor will it affect others to call your interface functions;

​

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Python __name__ == ‘__main__

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