*args and **kwargs in python (python basic learning)

*args and **kwargs in python (python basic learning)

---

---

---

文章抄自*args and **kwargs in Python (Python Basic Learning) - CSDN - Dust on Dandelion ，仅用作个人学习和记录。如有帮助，请关注原作者，给原作者点赞。

---

1. Meaning

1. *args and **kwargs are mainly used to define the variable parameters of the function
2. *args: Send a variable number of non-key-value arguments to the function
3. **kwargs: Send a variable number of argument lists of key-value pairs to the function
4. If you want to use named variables (like dictionaries) inside a function, use **kwargs

The purpose of defining variable parameters is to simplify
the role of calling * and ** here: packing parameters

2. Precautions when using

1. *args and **kwargs are not fixed, only the front * and ** are fixed and immutable, and the latter names can be changed at will. For example, *vals represents a variable number of parameters that are not key-value pairs, and **parms represents variable parameters. Variable number of key-value pair arguments. Using *args and **kwargs is a customary convention, and you don't have to use this name.
2. When using *args and **kwargs at the same time, *args must be written before **kwargs.

def test_args(*args):
	print(args)

def test_kwargs(**kwargs):
	print(kwargs)
	print(type(kwargs)
	for key, value in kwargs.items():
		print("{} == {}".format(key, value))

def test_all(*args, **kwargs):
	print(args)
	print(kwargs)

• Pack multiple parameters 'name', 'age', 'address', 'sex' received by the function test_args() into a tuple ('name', 'age', 'address', 'sex'), Assigned to the formal parameter args.

test_args('name', 'age', 'address', 'sex')

"""输出结果
('name', 'age', 'address', 'sex')
"""

test_kwargs(name='zxf', age=23, address='zhejiang')

"""输出结果
{'name': 'zxf', 'age': 23, 'address': 'zhejiang'}
<class 'dict'>
name == zxf
age == 23
address == zhejiang
"""

test_all('name', 'age', name='zxf', age=23)

"""输出结果
('name', 'age')
{'name': 'zxf', 'age': 23}
"""