python中什麼是*args和**kwargs？

def foo(*args, **kwargs):
    print('args = ', args)
    print ('kwargs = ', kwargs)
    print('---------------------------------------')

if __name__ == '__main__':
    foo(1,2,3,4)
    foo(a=1,b=2,c=3)
    foo(1,2,3,4, a=1,b=2,c=3)
    foo('a', 1, None, a=1, b='2', c=3)

輸出結果
args = (1, 2, 3, 4)

kwargs = {}

args = ()

kwargs = {‘a’: 1, ‘b’: 2, ‘c’: 3}

args = (1, 2, 3, 4)

kwargs = {‘a’: 1, ‘b’: 2, ‘c’: 3}

args = (‘a’, 1, None)

kwargs = {‘a’: 1, ‘b’: ‘2’, ‘c’: 3}

這兩個是python中的可變參數，*args代表元祖tuple **kwargs代表的是字典dict
並且同時使用*args和**kwargs時，必須*args參數列要在**kwargs前，像foo(a=1, b=’2’, c=3, a’, 1, None, )這樣調用的話，會提示語法錯誤“SyntaxError: non-keyword arg after keyword arg”。