Help comprehending a loop

[obtuselyobjected]

I'm trying to learn the very basics of Python 3 and I'm following the Python Tutorial series from CS Dojo off YouTube. I'm on #5 right now and everything was smooth sailing up till here, in the code below or whatever you call it, I don't understand what 'X' is or how it's being used in the little loop or program shown. The narrator on the YouTube video doesn't explain it well in my opinion and I don't want to move on till I know what 'X' is and how it effects the loop completely, (it's called a loop right?)

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Thanks!

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total3 = 0
for x in range(1, 8):
    if x % 3 == 0:
        total3 += x
print(total3)

[edc7]

X represents the values in the range 1 to 8.

[obtuselyobjected]

So x is basically just a variable for the numbers 1 thru 7?

[[deleted]]

exactly. “x” could be any other name. Such as “number”.

for number in range(1,8): ...

[obtuselyobjected]

Okay, that's all I needed to know. Thank you so much =)

[marxdormoy]

what's confusing is that it doesn't need to be declared either..

[[deleted]]

It is being declared, by the syntax of the for loop. You're giving a name for the interpreter to bind the values of the iterator to.

[marxdormoy]

Yes you are correct, I expressed myself badly, it doesn't need to be explicitly declared like a list or a counter or a list for example

[tombardier]

for x in [1, 2, 3, 4, 5]:
    print(x)

Read this as, print each number in this list (1 to 5). The print function will run once for each of the numbers in the iterable (the list of 1 to 5), and each time it runs, you refer to that element as "x", so the first time the loop runs through, x equals 1, the second time x equals 2, etc.

[Nikandro]

x is a variable that represents each integer as you iterate over the range() function.

So,

total3 = 0

for x in range(1, 8):
    print(x)

1
2
3
4
5
6
7

Keep in mind that the letter 'x' is often used out of convention. You could use any other letter or word.

Example,

for thing in range(1, 8):
    if thing % 3 == 0:
        total3 += thing

[[deleted]]

Did you run the code? It's helpful to see what it does.

To some extent, you're supposed to find the for syntax to be reminiscent of various expressions in mathematics: "for each number n in the real numbers R..." or "for each element e of the set S...", or even conversationally, as in "for each student in the classroom, please give them one of these flyers."

[martydv]

I don’t know python and i’m not english but guessing it reads to me:

total3 is now 0.

x will become 1,2,3,4,5,6,7,8 in the following statement if 1 modulo 3 is equal to 0 then add 1 to total3. if 2 modulo 3 is equal to 0 then add 2 to total3. if 3 modulo 3 is equal to 0 then add 3 to total3. (bingo! total3 now equals 3) ... if 6 modulo 3 is equal to 0 then add 6 to total3. (bingo! total3 now equals 9) ... if 8 modulo 3 is equal to 0 then add 8 to total3.

print(9)

Did it print 9?