What is fuction of '*' and '**' in python??(list, dict, etc)

Question

Explain Function of *args and **kwargs and where they can be used.

Answer 1

def foo(a, *b, **c) :
print(a)
print(b)
print(c)

foo(1,2,3,num=4,age=15)

#output
1
(2, 3)
{'num': 4, 'age': 15}

*args is used when you need "not predefined length of function arguments".
In the example, the first argument will be assigned to "a" as usual. and the rest of the arguments will all be assigned to *args (*b), which is a tuple. **kwargs means keyword arguments, this kind of arguments will be assigned, if the user of this function enter something like xxx=ooo. **kwargs (**c) is a dictionary.

Remember that kwargs should always placed after args when using the function.

Answer 2

GODOFPC I just looked at those * and ** and I gave answer. 😅

Answer 3

1_coder Yes it works Thanks😄

Answer 4

Thanks Again😃🙃李立威

Answer 5

Great Explaination 👏

Answer 6

* is used for multiplication and ** is used to represent power.

example.
2 * 3 = 6(2 * 3),
but
2 ** 3 = 8(2 * 2 * 2)

Answer 7

Raj Chhatrala Bro I mean in lists
*args and **kwargs
if we print a list with asterisk before then square brackets will be gone and commas too
But I dont know the functuon of **kwargs and their proper use

BTW Thnxx for ur attention🙂

Answer 8

Raj Chhatrala Its ok
Actually I forgot to mention lists😅

Answer 9

李立威 Thanks 🤩👍
Very nice Explaination 👏
Its clear to me now✌️

Answer 10

Oh, another usage of * before a list or any multiple elements data works like this.

tup=(1, 2, 3)
print(*tup)

#output
1 2 3

First, note that *tup can only be used in another function or method,( i. e. writing *tup itself without wrapped in another function such as print is a syntax error). Given "tup" to be any data structure that may contain multiple elements in Python (e. g. list, tuple, dictionary, set and even generator). f(*tup) will first unwrap all the elements within tup, and then throw them back into the function f. At this point, if the function "f" takes exactly 3 arguments for example, but len(tup) is not 3, it will cause an error. This is a situation when we need "not pre-defined length of arguments" in a function.

For example, print(*tup) is equivalent to print(1,2,3)

A good way for me to memorize these usage, is that the * (asterisk) sign means "all" in many cases. Reminds something like:
from OOO import *
The * sign means "all".

Answer 11

A related use of * is for unpacking.

a, b, *c = (1, 2, 3, 4)
a == 1
b == 2
c == [3, 4]

Most commonly we use this to "consume" extra values from a function return when we only want the first one(s).

success, *_ = func_that_returns_mult_values()

Answer 12

* ex. 2*3=6
**ex. 2**3=8