Python基础系列之*args和**kwargs的认识

Python
留言

*args和**kwargs这两个参数咱们经常用到，今天在巩固基础的时候，看到了这两个参数，做了一下对比，所以记录一下。

*args

*args这种写法代表的是 元组，就比如我上面为啥说它们是参数，是因为他们经常在函数的参数中出现。
下面咱们在例子中来说明

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def getTupleParameter(x, *args):
    print('x is {}'.format(x)) 
    print('args is {}'.format(args))
    print('type is {}'.format(type(args)))
    for i in args:
        print('i is {}'.format(i))

getTupleParameter(1, 2, 3, 4, 5, 6, 7)

print('*'*100)
getTupleParameter(1)

结果

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x is 1
args is (2, 3, 4, 5, 6, 7)
type is <class 'tuple'>
i is 2
i is 3
i is 4
i is 5
i is 6
i is 7
********************************************************************
x is 1
args is ()
type is <class 'tuple'>

**kwargs

*kwargs这种写法代表的是 字典，下面咱们在例子中来说明

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def getDictParameter(x, **kwargs):
    print('x is {}'.format(x))
    print('kwargs is {}'.format(kwargs))
    print('type is {}'.format(type(kwargs)))

getDictParameter(1, a=1, b=2, c=3)
getDictParameter(1)
res = dict(
    a=1,
    b=2,
    c=3
)
getDictParameter(1, **res)

结果

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x is 1
kwargs is {'b': 2, 'a': 1, 'c': 3}
type is <class 'dict'>
x is 1
kwargs is {}
type is <class 'dict'>
x is 1
kwargs is {'b': 2, 'a': 1, 'c': 3}
type is <class 'dict'>

*args和**kwargs的混合使用

*args和**kwargs在程序中一起使用很常见

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def getTupleAndDict(x, *args, **kwargs):
    print('x is {}'.format(x))
    print('kwargs is {}'.format(kwargs))
    print('args is {}'.format(args))
getTupleAndDict(1, 2, 3, 4, 5, A=1, B=2, C=3, D=4)

结果

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x is 1
kwargs is {'D': 4, 'C': 3, 'A': 1, 'B': 2}
args is (2, 3, 4, 5)