Meaning of python variables preceded by a star (*)
1. When constructing a function, add * in front of the variable to represent receiving parameters in the form of tuples.
def func(*args)
2, used to construct arrays, can be seen as a generator, and constantly will be input one by one to generate things out.
importation(1,2)，Then, in turn, it produces1,2 importation[1,2]，Then, in turn, it produces1.2 v1 = (1,2) v2 = [3,4] ([0,*v1]) ([*v2]) ([0,*v1,*v2])
3, constructor when the form of the parameter before adding two **, on behalf of receiving the dictionary form of the parameters.
def func(**args)
Adding an asterisk (*) to parameters in Python methods
Simply put, an asterisk represents an "unpacking" operation.
This is illustrated below using examples:
Use of single asterisks
arr = [0, 1, 2, 3] # (0, 1, 2, 3) results are consistent
def count(*s):
print(s)
count(*arr)
# in the end：(0, 1, 2, 3)A single asterisk treats the parameter s as atupletype, care is needed when performing the operation.
arr = {'a': 0, 'b': 1, 'c': 2, 'd': 3}
def count(*s):
print(s)
count(*arr)
# in the end：('a', 'b', 'c', 'd')When we pass in an argument that is originally a dictionary type, the argument s represents the key of the dictionary.
Use of double asterisks
arr = {'a': 0, 'b': 1, 'c': 2, 'd': 3}
def count(**s):
print(s)
count(**arr)
# in the end：{'a': 0, 'b': 1, 'c': 2, 'd': 3}A double asterisk treats the argument s as adictionariesThe following are some examples of the types of dictionaries that can be used.
summarize
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