What is [ if __name__=="__main__"] in python ??

 

consider a function func1 as shown (1) such that it takes a string value and returns an f-string with that specific value Now if we simply print this function then we will obtain the result (2)

Now let us introduce our if __name__=="__main__" function in our line of code for introducing let us before make another python file and import this current python file and use a print function to understand the execution of the code in that file (3) now if you see the output in (4) then a common question may arise that why the {Say hello to john} is printed here even though in your main2.py file there is no such print function which will give that output this happens because of the import function which as a whole import the whole lines of code from the main.py file thus resulting in the printing of the output from the previous file 

So that's the time where our if __name__=="__main__" is used it is basically used to stop the full execution of the import file and yet helps in guiding the import function which part to import and which part is not to import 

Now after the introduction of the if __name__=="__main__" file in our main.py file if we now run the main2.py file then we will get an output (6) so you can now understand that the if__name__=="__main__" file simply stops the execution of the file that was present inside it due to which two outputs were not printed like in the earlier case 

(1)[main.py] def func1(string):

return f"Say hello to {string}"

string="john"

print(func1(string))

(2)Output: Say hello to john

(3)[main2.py]import main

print(main.func1("Robert"))

(4)Output: Say hello to john Say hello to Robert

(5)[main.py]def func1(string):

return f"Say hello to {string}"

if __name__=="__main__":

string="john"

print(func1(string))

(6)Output:Say hello to Robert