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Python中*args 和**kwargs的用法

Python中args 和kwargs的用法
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。

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  

**kwargs:

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  

也可以用下面的形式:

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  




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

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