45.不定长参数字典

def functionname([formal_args,] *args, **kwargs):
   """函数_文档字符串"""
   function_suite
   return [expression]

>>> def fun(a, b, *args, **kwargs):
...     """可变参数演示示例"""
...     print("a =%d" % a)
...     print("b =%d" % b)
...     print("args:")
...     print(args)
...     print("kwargs: ")
...     for key, value in kwargs.items():
...         print("key=%s" % value)
...
>>> fun(1, 2, 3, 4, 5, m=6, n=7, p=8)  # 注意传递的参数对应
a = 1
b = 2
args:
(3, 4, 5)
kwargs: 
p = 8
m = 6
n = 7
>>>
>>>
>>>
>>> c = (3, 4, 5)
>>> d = {"m":6, "n":7, "p":8}
>>> fun(1, 2, *c, **d)    # 注意元组与字典的传参方式
a = 1
b = 2
args:
(3, 4, 5)
kwargs: 
p = 8
m = 6
n = 7
>>>
>>>
>>>
>>> fun(1, 2, c, d) # 注意不加星号与上面的区别
a = 1
b = 2
args:
((3, 4, 5), {‘p‘: 8, ‘m‘: 6, ‘n‘: 7})
kwargs:
>>>
>>>

def sum_nums_3(a, *args, b=22, c=33, **kwargs):
    print(a)
    print(b)
    print(c)
    print(args)
    print(kwargs)

sum_nums_3(100, 200, 300, 400, 500, 600, 700, b=1, c=2, mm=800, nn=900)

100
1
2
(200, 300, 400, 500, 600, 700)
{‘nn‘: 900, ‘mm‘: 800}

# 不定长参数元组
# def func1(*args):
#     pass

# 位置参数调用函数
# 需求: 不知道传入多少个实参 但是我还想需要通过关键字参数调用函数
def func(**kwargs):
    # <class ‘dict‘>
    print(type(kwargs))
    print(kwargs["name"])
    print(kwargs["age"])
    print(kwargs["no"])
# 函数的调用
func(name="小红", age=18, no="009")

# 注意点:
# 不定长参数字典 也是一个缺省参数 默认值为一个空的字典
def func(**kwargs):
    print(len(kwargs))
func()