if __name__ == "__main__"如何正确理解

粗略来讲，__name__是当前模块，当模块被直接运行时模块名为__main__。这句话的意思是，当模块被直接执行时，代码将运行，当模块是被导入时，代码不被运行

例如，执行one.py

 # file one.py
 def func():
     print("func() in one.py")

 print("top-level in one.py")

 if __name__ == "__main__":
     print("one.py is being run directly")
 else:
     print("one.py is being imported into another module")

　　运行结果：

　　执行two.py:

 # file two.py
 import one

 print("top-level in two.py")
 one.func()

 if __name__ == "__main__":
     print("two.py is being run directly")
 else:

　　运行结果：