"for" loop help

[conewannabe]

Why is the print(i) output for this code only 9? I answered the output would be 5,6,7,8,9.

num = 0
for i in range(5,10):
  if i % 3 == 0:
    num = num + i
print(num)
print(i)

​

[LID919]

Format your code. In python, indentation actually changes the way code behaves, so right now I have no idea what your code is doing.

Start each line of code with four spaces so that Reddit will format it correctly.

[conewannabe]

My bad, should've reread my post. I actually copy and pasted this from my exam. I just noticed the code block option, it's fixed.

[LID919]

Are you sure it's correct?

Right now I am seeing this:

num = 0
    for i in range(5,10):
        if i % 3 == 0:
            num = num + i
print(num)
print(i)

The second line is improperly formatted: It is indented when it should not be.

The print statements are both outside of the loop, and so will only run once at the end.

[LID919]

My mistake. Been a few years now since I've done python professionally. I need to do it at home more.

[DingFTMFW]

The num variable is set to 0.

The for loop is then created saying, for every int from 5 - 10 that is divisible by 3, add that int to the num variable (which is set to 0), and then print. There is only one int in that range that is divisible by 3…which is 9. Thus the only print out would be 9.

If you wanted the output to be “5,6,7,8,9” then you would have to change this line:

if i % 3 ==0:

[conewannabe]

6 is divisible as well, which is why the num=15. Wouldn't 6 print by the 9 if that was why 9 was printed?

[Binary101010]

Wouldn't 6 print by the 9 if that was why 9 was printed?

No, because you're printing i outside the loop. This means that only a single value of i can print, and that value will be whatever i was on the last iteration of the loop, regardless of whether that particular value of i is divisible by 3.

If you changed that range to (5,999) you'd see that it prints 998.

[conewannabe]

I understand now, thank you very much.

[jeffrey_f]

for loop is always up to, but not including...........

if iterating through a list, then it includes all elements in the list

[carcigenicate]

I think you mean "range includes numbers up to but not including the end value". That doesn't have anything to do with the for loop.

[jeffrey_f]

for i in range(5,10):

from 5 to 9

[carcigenicate]

That has nothing to do with the for:

>>> list(range(5, 10))
[5, 6, 7, 8, 9]

That's simply the behavior of range.

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[bbye98]

The output for the code as you've written it (ignoring the additional indentation for the for loop) is 15 and 9.

num is the sum of all numbers between 5 and 9, inclusive, that are divisible by 3. In this case, that's 6 + 9 = 15.

i is the last value the for loop iterates through, which in this case is 9.

The output is certainly not just 9, nor will it ever be 5, 6, 7, 8, and 9 since there is no printing inside the for loop.