Python function variable parameter definition and its parameter passing method details
In python, a function with an indefinite parameter is defined as follows
1、 func(*args)
The incoming arguments are in args in the form of tuples, e.g.:
def func(*args): print args >>> func(1,2,3) (1, 2, 3) >>> func(*[1,2,3]) # This way you can directly treat all the elements of a list as indeterminate arguments transmitted inwards(1, 2, 3)
2、func( **kwargs)
The incoming arguments are in args in dictionary form, e.g.:
def func(**kwargs):
print kwargs
>>> func(a = 1,b = 2, c = 3)
{'a': 1, 'c': 3, 'b': 2}
>>> func(**{'a':1, 'b':2, 'c':3}) # This way you can directly pass all key-value pairs of a dictionary as keyword arguments to the
{'a': 1, 'c': 3, 'b': 2}
3, you can also mix the two func(*args, **kwargs)
The order of passing in must be the same as the order of definition, in this case an indefinite parameter list followed by a dictionary of keyword parameters, for example:
def func(*args, **kwargs):
print args
print kwargs
>>> func(1,2,3)
(1, 2, 3)
{}
>>> func(*[1,2,3])
(1, 2, 3)
{}
>>> func(a = 1, b = 2, c = 3)
()
{'a': 1, 'c': 3, 'b': 2}
>>> func(**{'a':1, 'b':2, 'c':3})
()
{'a': 1, 'c': 3, 'b': 2}
>>> func(1,2,3, a = 4, b=5, c=6)
(1, 2, 3)
{'a': 4, 'c': 6, 'b': 5}</span>
# It's not okay to jump around like this
>>> func(1,2,3, a=4, b=5, c=6, 7)
SyntaxError: non-keyword arg after keyword arg
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