python函数参数*args**kwargs用法实例

# 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 'args:',farg
    for value in args:
        print 'another arg:',value

# *args可以当作可容纳多个变量组成的list或tuple
fun_var_args(1,'two',3,None)

#args: 1
#another arg: two
#another arg: 3
#another arg: None

def fun_var_kwargs(farg,**kwargs):
    print 'args:',farg
    for key in kwargs:
        print 'another keyword arg:%s:%s' % (key,kwargs[key])

# myarg1,myarg2和myarg3被视为key， 感觉**kwargs可以当作容纳多个key和value的dictionary
fun_var_kwargs(1,myarg1='two',myarg2=3,myarg3=None)
# 输出：
#args: 1
#another keyword arg:myarg1:two
#another keyword arg:myarg2:3
#another keyword arg:myarg3:None

def fun_args(arg1,arg2,arg3):
    print 'arg1:',arg1
    print 'arg2:',arg2
    print 'arg3:',arg3

myargs = ['1',None]     # 定义列表
fun_args(*myargs)

# 输出：
#arg1: 1
#arg2: two
#arg3: None

mykwargs = {'arg1': '1','arg2': 'two','arg3': None}      # 定义字典类型
fun_args(**mykwargs)

# 输出：
#arg1: 1
#arg2: two
#arg3: None

# 两者都有
def fun_args_kwargs(*args,args
    print 'kwargs:',kwargs

args = [1,2,4]
kwargs = {'name': 'BeginMan','age': 22}
fun_args_kwargs(args,kwargs)
# args: ([1,4],{'age': 22,'name': 'BeginMan'})
# kwargs: {}

fun_args_kwargs(1,a=100)
#args: (1,3)
#kwargs: {'a': 100}

fun_args_kwargs(*(1,4),**{'a':None})
#args: (1,4)
#kwargs: {'a': None}