How to pass values for a function in python?

Question

I have started learning python.

I don't know how to pass values for function?

Here is the code:

def summation(*numbers):
    add = 0
    for y in numbers:
        add = add + y
    return add


n = int(input("How many numbers you want to add: "))
for x in range(1, n + 1):
    int(input("Enter number: "))
print("Sum:", summation())

print("Sum:", summation()) How can I pass for summation?

Store the user input in a list, then pass that list to the function. — 001, Jul 09 '20 at 13:57
Is the asterisk a typo, or pointer? Pointers are done with a asterisk in C++ also. — cs1349459, Jul 09 '20 at 13:58

Skander HR · Accepted Answer · 2020-07-09T14:02:06.887

1

def summation(numbers):
    add = 0
    for y in numbers:
        add = add + y
    return add


n = int(input("How many numbers you want to add: "))
row_nums = []
for x in range(1, n + 1):
    row_nums.append(int(input("Enter number: ")))
print("Sum:", summation(row_nums))

I just did a quick tweak to your code. Also, you have to store your numbers while reading them.

I put a variable when declaring the function without choosing its type. and use it in my code as a list. Python is not a strongly typed language.

edited Jul 09 '20 at 14:02

answered Jul 09 '20 at 13:58

Skander HR

580
3
14

2

Add an explaination to your answer, so people will understand it. – cs1349459 Jul 09 '20 at 14:00
Since `x` is not being used, `range(n)` gives the same number of iterations as `range(1, n + 1)`. – Jul 09 '20 at 14:04

score 1 · Answer 2 · answered Jul 09 '20 at 14:11

As you were told in comment, it is enough to store the numbers in a list. The you can pass the values of the list by prefixing it with a *:

n = int(input("How many numbers you want to add: "))
# the pythonic way to build a list is a comprehension:
numbers = [int(input("Enter number: ")) for x in range(n)]
print("Sum:", summation(*numbers))

score 0 · Answer 3 · answered Jul 09 '20 at 13:59

You could just turn the way you get the numbers into a generator:

In [2]: def numbers(): 
   ...:     n = int(input("How many numbers you want to add: ")) 
   ...:     for x in range(1, n + 1): 
   ...:         yield int(input("Enter number: ")) 

In [4]: print("Sum:", summation(*numbers()))                                                                                  
How many numbers you want to add: 3
Enter number: 1
Enter number: 2
Enter number: 3
Sum: 6

score 0 · Answer 4 · answered Jul 09 '20 at 14:07

What you are looking for are variable arguments for a function:

def summation(*args):   # notice how the asterisk 
                        #   is used to signify variable arguments
    sum = 0
    for y in args:
        sum = sum + y
        # sum += y
    # Or simply
    # return sum(args)
    return sum

n = int(input("How many numbers you want to add: "))

# We will record users input in this set
numbers = set() 

for x in range(1, n + 1):
    # Here we keep a record of users input
    numbers.add(int(input("Enter number: "))) 

print("Sum:", summation(*numbers)) # Finally we pass 
                                   #  in the whole set tot he function

Notice how the asterisk is used to pack and unpack a tuple.

If you'd like to learn more about the concept, you can google for the keywords above or start from this excellent article.

How to pass values for a function in python?

4 Answers4