What is main() here?

Question

I've seen code such as:

if __name__ == "__main__":
    main()

What does main() mean there? Is it a function of some sort?

Answer 1

main() is a function. However, you need to define it. If you have ever used another programming language, such as Java, C, or C++, you'd have heard of a main method. You define your own main method, then tell Python to use it immediately. It is typically just for good practice, so for example

if __name__ == "__main__":
    main()

def main():
    print("Hello, World")

Is the same as

print("Hello, World")

Later on in your Python career, you will learn the benefits of this script.

Answer 2

Its your main function You should add

def main():
    blabla...

Answer 3

example1.py

print ("Always executed example1")

def main(param):
    print(param)

if __name__ == "__main__":
    print ("Executed example1 when invoked directly ")
    main('main invoked directly')

else:
    print ("Executed example1 when imported")
    main('main invoked when imported')

example2.py

import example1

if __name__ == "__main__":
    print ("Executed example2")
    example1.main('main invoked from example2 __name__')

Output when example1.py runs:

Always executed example1
Executed example1 when invoked directly 
main invoked directly

Output when example2.py runs:

Always executed example1
Executed example1 when imported
main invoked when imported
Executed example2
main invoked from example2 __name__

In simple words: main() is jus a function defined and if it's under under if __name__ == "__main__":, will only get called upon when your Python file is executed as python example1.py

However, if you wish to import your Python file example1.py as a module to work with another Python file, say example2.py, the code under if __name__ == "__main__": will not run or take any effect.