“if __name__ == __main__:”的作用:指定主方法函数。在脚本执行时开启main函数,但是在其他文件import调用时不会执行。
一个python的文件有两种使用的方法,第一是直接作为脚本执行,第二是在其他文件的python脚本中被import即调用(模块重用)执行。因此if name == 'main':的作用就是控制这两种情况执行代码的过程,在if name == 'main':下的代码只有在第一种情况下(即文件作为脚本直接执行)才会被执行,而import到其他脚本中是不会被执行的。
例子:
# file one.pydef 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")
# file two.pyimport one # start executing one.pyprint("top-level in two.py") one.func()if __name__ == "__main__": print("two.py is being run directly")else: print("two.py is being imported into another module")
当运行python one.py,输出:
top-level in one.py one.py is being run directly
当运行python two.py,输出:
top-level in one.py one.py is being imported into another module top-level in one.pyfunc() in one.py two.py is being run directly
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