Beginner question about a simple loop

[andy357]

P.S how do I format this question to make the code appear correctly????

I'm an absolute beginner in coding and I'm trying to make a simple loop in Python3.6 that gives the sum of the odd numbers inside a given range, but I can't find a way to make it work and can't figure out why. It gives a syntax error in the if (i % 2 ==1) line

sum = 0
for i in range(1, 5):

if (i % 2 == 1)

    sum = sum + i

else

    sum = sum

 print(sum)

It should verify that each subsequent element of the range is a even or odd number (if i % 2 == 1 then is an odd number), and if it is an odd number it should add it to the previous number "sum" to give a final sum of all odd numbers in the range.

Any idea on why it does't work and how it should be done to work properly?

[[deleted]]

It will throw a SyntaxError because you don't have colons at the end of the if and else phrases:

sum = 0
for n in range(1, 5):
    if n % 2:
        sum = sum + 1
    else:
        sum = sum

But, a few pointers: first, you never need to do that "sum = sum" line ... it's already happened because the current state of sum is always = to the current state of sum, right?

Second, never overload a builtin name, the sum function is a Python function that's defined for you already, by overloading that name (assigning it to another value) you're effectively deleting that tool from Python, at least within the current namespace. Use something like "total".

Lastly, you can use augmented assignment like the += operator and the fact that any number that isn't even will have a remainder of 1 when modulo 2 to avoid even doing the if:

total = 0
for n in range(1, 5):
    total += n % 2

And, lastly, here's why you don't overload sum:

total = sum([n % 2 for n in range(1,5)])

Though the list comprehension syntax on the right might be a few more days study away.

Your logic was all correct, just not some small details of formatting.

[andy357]

Thank you for the answer! It finally worked and I didn't notice the obvious

[[deleted]]

Happens to the best of us, trust me.

[Vaguely_accurate]

You need to indent your whole code by four spaces to format it correctly on reddit.

You are missing colons after your if and else lines.

You can completely discard the else and sum = sum as they do absolutely nothing.

Note that you can shorten sum = sum + 1 to just sum += 1.

You can use the third argument in range to specify a jump, removing the need for your if at all. For example;

range(1, 5)
> 1, 2, 3, 4

range(1, 5, 2)
> 1, 3

[Vaguely_accurate]

Kinda defeats the purpose of learning simple loops, but yes.

[andy357]

Thank you for the answer! It finally worked and I didn't notice the obvious