Python中*args 和**kwargs的用法和区别

当函数的参数是可变参数是，使用*args和**kwargs。其中*args对应的可变参数不含key，而**kwargs对应的可变参数含有key。

*args的使用：

>>> def fun1(*args):
...     for item in args:
...             print item
... 
>>> fun1(1, 'hello', True)
1
hello
True

或者：

>>> def fun1_1(arg1, arg2, arg3):
...     print arg1
...     print arg2
...     print arg3
... 
>>> args = ['hello', 3]
>>> 
>>> fun1_1('test', *args)
test
hello
3

**kwargs的使用:

>>> def fun2(**kwargs):
...     for k in kwargs:
...             print "%s:%s" % (k, kwargs[k])
... 
>>> fun2(hello=1, world=2, welcome=3)
world:2
welcome:3
hello:1

或者：

>>> def fun2_2(arg1, hello, world):
...     print 'arg1:', arg1
...     print 'arg2:', hello
...     print 'arg3:', world
... 
>>> kwargs = {'hello':3, 'world':2}
>>> fun2_2(1, **kwargs)
arg1: 1
arg2: 3
arg3: 2