Answers for "python if __name__ == '__main__':"

if __name__ == '__main__'

if __name__ == "__main__":

__name__== __main__ in python

# If the python interpreter is running that module (the source file)
# as the main program, it sets the special __name__ variable to have
# a value “__main__”. If this file is being imported from another 
# module, __name__ will be set to the module’s name.
if __name__=='__main__':
  # do something

What does if __name_=="_main__": do?

# Suppose this is foo.py.

print("before import")
import math

print("before functionA")
def functionA():
    print("Function A")

print("before functionB")
def functionB():
    print("Function B {}".format(math.sqrt(100)))

print("before __name__ guard")
if __name__ == '__main__':
    functionA()
    functionB()
print("after __name__ guard")

what is __name__ == "__main__":

Every Python module has it's __name__ defined and if this is '__main__', it implies that the module is being run standalone by the user and we can do corresponding appropriate actions. If you import this script as a module in another script, the __name__ is set to the name of the script/module.