Python中*args 和**kwargs的用法

转：http://blog.csdn.net/chenjinyu_tang/article/details/8136841

当函数的参数不确定时，可以使用*args 和**kwargs，*args 没有key值，**kwargs有key值。

还是直接来代码吧，废话少说

（1）*args例子：

    def fun_var_args(farg, *args):  
        print "arg:", farg  
        for value in args:  
            print "another arg:", value  
      
    fun_var_args(1, "two", 3) # *args可以当作可容纳多个变量组成的list  

result:

 arg: 1

another arg: two

another arg: 3  

（2）**kwargs例子：

    def fun_var_kwargs(farg, **kwargs):  
        print "arg:", farg  
        for key in kwargs:  
            print "another keyword arg: %s: %s" % (key, kwargs[key])  
      
      
    fun_var_kwargs(farg=1, myarg2="two", myarg3=3) # myarg2和myarg3被视为key， 感觉**kwargs可以当作容纳多个key和value的dictionary  

result：

    arg: 1  
    another keyword arg: myarg2: two  
    another keyword arg: myarg3: 3  

（3）也可以是用下面方式：

    def fun_var_args_call(arg1, arg2, arg3):  
        print "arg1:", arg1  
        print "arg2:", arg2  
        print "arg3:", arg3  
      
    args = ["two", 3] #list  
      
    fun_var_args_call(1, *args)  

result：

arg1: 1  
arg2: two  
arg3: 3 

（4）**kwargs方式二

    def fun_var_args_call(arg1, arg2, arg3):  
        print "arg1:", arg1  
        print "arg2:", arg2  
        print "arg3:", arg3  
      
    kwargs = {"arg3": 3, "arg2": "two"} # dictionary  
      
    fun_var_args_call(1, **kwargs)  

result：

    arg1: 1  
    arg2:"two"  
    arg3:3