[Tutor] Getting total of a list (newbie)

[Danny Yoo]

On Tue, 11 Sep 2001 Brmfq@aol.com wrote:

> num = input("Please enter a number:")
> tot = [num]
> while len(tot) < 10:
>      nex = input("Please enter another number: ")
>      tot.append (nex)
> print 'total of 10 numbers is', 
> tot[0]+tot[1]+tot[2]+tot[3]+tot[4]+tot[5]+tot[6]+tot[7]+tot[8]+tot[9]
> 
> This works, but it's only for 10 numbers. Could someone please show me
> a better way? Thanks in advance to anyone who replies.


Hello!  Have you learned about functions yet?  We can write a sumUp()
function that takes in a list, and returns its total:

###
def sumUp(numbers):
    total = 0
    for n in numbers:
        total = total + n
    return total
###


What makes this function so useful is that now we can use it for your
program:

###
print 'total of 10 numbers is', sumUp(numbers)
###



for random, gratuitous summations:

###
>>> sumUp(range(10))
45
###


or even for the definitions of other functions:

###
def average(numbers):
    return sumUp(numbers) / float(len(numbers))
    ## float() might be necessary because of possibility
    ## of integer division (as of Python 2.1.1)
###


Only our sumUp() function has to do this "sum" thing.  When we make a
sumUp() function, we can treat the summing of lists as a new tool that we
can fiddle with.

As you can tell, I'm something of a function fanatic.  *grin*


If you have more questions, please feel free to ask.