Python中*args 和**kwargs的用法

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

當函數的參數不確定時，可以使用*args 和**kwargs，*args 沒有key值，**kwargs有key值。

還是直接來代碼吧，廢話少說

（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可以當作可容納多個變量組成的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被視為key， 感覺**kwargs可以當作容納多個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