How to Use Main Function in Python with Example

 

Students want to know how to use the main function in Python. Here our experts will explain to you in detail with an example.

What Is The Main Function in Python And How to Use Python Function?

Every programming language have a main() work as a pre-defined technique to show to the compiler that it is the start of the execution stream. The Python language is a special case to this, as its execution is in a sequential way. And the principal line of the code will be the beginning stage naturally.

Notwithstanding of main() function not being a required component. If the software engineer wishes to have a principle strategy to order different pieces of code. Generally, make a client-characterized technique, which will work like different strategies in Python.

Check out this blog for complete pieces of information. Regarding what is the main function in python and how to use the Python function.

What is the Main Function in Python 

The main functions resemble the program entry point. However, the Python translator runs the code directly from the principal line. The code execution begins from the beginning line and goes line by line. Also, it doesn’t make a difference where the main function is available or whether it is available or not. 

How to define the Python Main Function?

It is determined as a function in Python, much like how different functions are described.

Basic main function:

Print(‘Introduction to the main() function’)

def main():

print(“It is the main function”)

Print(‘Outside main function’)

Output: demo.py

>>>

=== RESTART: C:/Users/hp/AppData/Local/Programs/Python/Python37-32/demo.py ===

Introduction to main() function

Outside main function

>>>

Explanation:

From the head of the file, the Python interpreter begins execution. The first thing that will be printed will be the primary print statement statement. This article introduces the main() function. Following that, it discovers the definition of main(). There is no function call, since it is just a small definition. Consequently, it ignores this and executes the print statement that follows.

Note: In python, it is not important the name ‘main’ method as main(). It can be determined with any actual identifier name like main(), main1(), etc.

Main() Execution needs a detailed knowledge of the __name__ variable.x

Brief about __name__ variable:

Variable __name__ is a unique absolute variable that includes a string value and string, that will be depending on how the code is executed.

Essentially there are two methods in which python translator executes code and the __name__ value is populated by this.

1. A popular method for handling files is through Python scripts

In this case, __name__ will include the string “__main__”

2. The required code can be carried from a Python file to a different Python file.

In this case, __name__ will incorporate the imported module name

__name__ variable supports to verify if the file of python is being run immediately or if it has been introduced from some different file.

Main function as Module 

Subsequent to bringing the script of Python as a module the variable __name__ gets the deserving equivalent to the name of the imported python content.

For example:

Let’s suppose there are two files (File3.py and File4.py). File3 is as follows.

# File3.py 

Print(“File3 __name__ = %s” %__name__)

If __name__ == “__main__”: 

 Print(“File3 is being run directly”)

Else: 

 Print(“File3 is being imported”)

Output:

File1 __name__ = __main__

File1 is being run directly

Now, when File3.py is imported into File4.py, the value of __name__ changes.

# File4.py 

Import File3

Print(“File4 __name__ = %s” %__name__)

If __name__ == “__main__”:

 Print(“File4 is being run directly”)

Else: 

 Print(“File4 is being imported”)

Therefore, it can be assumed that if __name__ == “__main__” is the program part that is executed when the script is run from the command line utilizing a command like Python File3.py.

Conclusion

The purpose of this post is to provide all the relevant information about what is the main function in Python and how to use it. Including data on what the functions are, how they are defined, and examples that illustrate their usage.