main function in python geeksforgeeks

During this process, the python interpreter sets the __name__ value to the module name if the Python source file is imported as a module. Here is an example module that consumes the __main__ namespace: Example usage of this module could be as follows: Now, if we started our program, the result would look like this: The exit code of the program would be 1, indicating an error. like this was imported from a different module, for example to unit test Python inserts an empty __main__ module in sys.modules at Most commonly, the __main__.py file is used to provide functions to execute from other modules. acknowledge that you have read and understood our, Data Structure & Algorithm Classes (Live), Data Structures & Algorithms in JavaScript, Data Structure & Algorithm-Self Paced(C++/JAVA), Full Stack Development with React & Node JS(Live), Android App Development with Kotlin(Live), Python Backend Development with Django(Live), DevOps Engineering - Planning to Production, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Taking multiple inputs from user in Python. Apply Filter Example 1: Input: N = 6 A[] = {3, 2, 1, 56, 10000, 167} Output: min = 1, max = 10000 Example 2: Know all About Robot Framework With Python. On evaluation to True, it executes main(). Django ModelForm Create form from Models, Django CRUD (Create, Retrieve, Update, Delete) Function Based Views, Class Based Generic Views Django (Create, Retrieve, Update, Delete), Django ORM Inserting, Updating & Deleting Data, Django Basic App Model Makemigrations and Migrate, Connect MySQL database using MySQL-Connector Python, Installing MongoDB on Windows with Python, Create a database in MongoDB using Python, MongoDB python | Delete Data and Drop Collection. There are two primary ways that you can instruct the Python interpreter to execute or use code: You can read a lot more about these approaches in How to Run Your Python Scripts. Neophyte to Advance. Please mention it in the comments section of Main Function In Python blog and we will get back to you at the earliest or join, Join Edureka Meetup community for 100+ Free Webinars each month. Python Object Oriented Programming (With Examples) By proactively following this convention ourselves, our module will have the name '__main__'. This conditional will evaluate to True when __name__ is equal to the string "__main__". Please tell me how main method works in python ? Why? With our online interpreter, you can test and debug your code in real-time, all from your web browser. For example: sys.exit(main()) As a result, programmers write all the necessary functional definitions on the top, and finally write this statement at the end, to organize the code. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? Practice | GeeksforGeeks | A computer science portal for geeks Get Hired with GFG Your Next Career Move Starts Here! On line 21, main() is defined. Why did US v. Assange skip the court of appeal? You may also see Python scripts executed from within packages by adding the -m argument to the command. On Windows, the command prompt typically looks like the example below: The part before the > may look different, depending on your username. Note that if you import the module again without quitting Python, there will be no output. In Python, an anonymous function means that a function is without a name. As a result, a module can discover whether or not it is running in the import. The first two lines of output are exactly the same as when you executed the file as a script on the command line because there are no variables in either of the first two lines. By importing the necessary code from one Python file to another. Python Functions (With Examples) - Programiz How to Install OpenCV for Python on Windows? It essentially serves as a starting point for the execution of a program. Python | Simple GUI calculator using Tkinter - GeeksforGeeks The details of how you can execute Python from your command line are not that important for the purpose of this article, but you can expand the box below to read more about the differences between the command line on Windows, Linux, and macOS. If you put a print statement before the if __name__ line then it will print output every time any other code attempts to import that as a module. Sometimes the code you write will have side effects that you want the user to control, such as: In these cases, you want the user to control triggering the execution of this code, rather than letting the Python interpreter execute the code when it imports your module. A-143, 9th Floor, Sovereign Corporate Tower, We use cookies to ensure you have the best browsing experience on our website. Since there is no main() function in Python, when the command to run a Python program is given to the interpreter, the code that is at level 0 indentation is to be executed. Please see this for details. This is my file to test Python's execution methods. What is Mutithreading in Python and How to Achieve it? Regular Expression in Python With Example, Object Oriented Programming Python: All you need to know, Python Class Object Oriented Programming. This is expanded upon a little more at python.berkely.edu, Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Hence, it is always good to call other functions from the main() itself. The commands that you type will go after the >. A Beginner's Guide to learn web scraping with python! What is print in Python and How to use its Parameters? However, there are slight differences in meaning that emphasize the purpose of a piece of code: File: Typically, a Python file is any file that contains code. If your .py file is primarily intended to be used as a module in other code then you might def test_module() and calling test_module() in your if __name__ == '__main__:' suite. The third print() will first print the phrase The value of __name__ is, and then it will print the representation of the __name__ variable using Pythons built-in repr(). Difference between Local variable and Global Variable - javatpoint 793k+ curious Nerds. However, there is a difference in the output from the third print(). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What is Random Number Generator in Python and how to use it? There are two main ways by which you can tell the Python interpreter to execute the code: Whatever the mode of execution you choose, Python defines a special variable called __name__, that contains a string. Python Basics: What makes Python so Powerful? When you import this file in an interactive session (or another module), the Python interpreter will perform exactly the same steps as when it executes file as a script. Map, Filter and Reduce Functions in Python: All you need to know. What are Important Advantages and Disadvantages Of Python? Correct. # for demonstration purposes, you can imagine that there is some, # valuable and reusable logic inside this function, """Echo the input arguments to standard output""", # next section explains the use of sys.exit. The if statement allows you to create a main function which will be executed if your file is loaded as the "Main" module rather than as a library in another module. we later package it as a console script entry-point in a pip-installable Binary Search | Practice | GeeksforGeeks (This happens in the background). It is time to apply it. __name__ is stored in the global namespace of the module along with the __doc__, __package__, and other attributes. Python dictionary is a built-in type that supports key-value pairs. What woodwind & brass instruments are most air efficient? There are mainly two types of functions in Python. Go produce the performance tree, by default, computer trusted on the library lxml. More often than not, some functions should be called as soon as the execution of the program starts. Complete this form and click the button below to gain instantaccess: "Python Tricks: The Book" Free Sample Chapter (PDF). In our example hashmap - Hash Map in Python - Stack Overflow When you run a Python module with python fibo.py <arguments> the code in the module will be executed, just as if you imported it, but with the __name__ set to "__main__". On the other hand, the Python interpreter executes scripts starting at the top of the file, and there is no specific function that Python automatically executes. This can be achieved using the name attribute of the module. Remember that the special value of "__main__" for the __name__ variable means the Python interpreter is executing your script and not importing it. How to Use Main Function in Python with Example - CodeAvail If you are not familiar with Python packages, see section Packages Manually raising (throwing) an exception in Python. The main () is considered a unique function for several programming languages, also referred to as the point of execution for a program file.

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