Python中*args和**kwargs 的简单使用

Posted 2020-09-05

# 在函数定义中使用*args和kwargs传递可变长参数. *args用作传递非命名键值可变长参数列表（位置参数）; kwargs用作传递键值可变长参数列表
# *args表示任何多个无名参数，它是一个tuple
# **kwargs表示关键字参数，它是一个dict

# 注：同时使用*args和**kwargs时，*args参数列必须要在**kwargs前

# eg _v1

def func(f,*args):
print ("formal arg:",f)
for f in args:
print ("another arg",f)

func(1,2,3,4)

# (‘formal arg:‘, 1)
# (‘another arg‘, 2)
# (‘another arg‘, 3)
# (‘another arg‘, 4)

# eg _v2

def functions(farg, **kwargs):
print ("farmal arg:",farg)
for key in kwargs:
print ("another keyword arg:%s: %s" % (key, kwargs[key]))

functions(farg=1,myarg2=2,myarg3=3,myarg4=4)
# (‘farmal arg:‘, 1)
# another keyword arg:myarg4: 4
# another keyword arg:myarg2: 2
# another keyword arg:myarg3: 3

# eg_v3

def functions(*args,**kwargs):
print ("args= ",args)
print ("kwargs= ",kwargs)
print ("+"*18)

if __name__ == "__main__":
functions(1,2,3,4,5)
# (‘args= ‘, (1, 2, 3, 4, 5))
# (‘kwargs= ‘, {})
# ++++++++++++++++++
functions(a=1,b=2,c=3,d=4)
# (‘args= ‘, ())
# (‘kwargs= ‘, {‘a‘: 1, ‘c‘: 3, ‘b‘: 2, ‘d‘: 4})
# ++++++++++++++++++
functions(1,2,3,a=1,b=2,c=3)
# (‘args= ‘, (1, 2, 3))
# (‘kwargs= ‘, {‘a‘: 1, ‘c‘: 3, ‘b‘: 2})
# ++++++++++++++++++