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。

还是直接来代码吧，废话少说

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