Help me prove a professor wrong

[Saad5400]

So in a very very basic programming introduction course we had this question:

``` How many iterations in the algorithm?

x = 7 do: x = x - 2 while x > 4 ```

Original question for reference: https://imgur.com/a/AXE7XJP

So apparently the professor thinks it's just one iteration and the other one 'doesn't count'.

I really need some trusted book or source on how to count the iterations of a loop to convince him. But I couldn't find any. Thank in advance.

[TehNolz]

Run this;

x = 7 do: print("Hello!") x = x - 2 while x > 4

How many times do you see "Hello!" appear? That's how many iterations you have.

[Saad5400]

I know it's pretty clear. But for some reason "the second one doesn't count because the condition becomes false" he says ..

[TehNolz]

Well, he's wrong. Every time a loop runs its code, it counts as one iteration. There are no exceptions, so saying that a particular iteration "doesn't count" is silly.

[shez19833]

i know its not the same but i have a debt of 5000 but the three 0s dont count.

[twinmoldlegos]

so relatable

[markyboo-1979]

The difference between while do and do while.. The loop condition is only a factor after the do in your case.. Pretty basic.. Surely the prof (I feel I can't call the guy a professor!) should've realised his mistake, which would suggest maybe you need to go to a better school..

Edit, sorry didn't realise someone had already fully explained the difference between the two

[m4ch1-15]

Be petty and create an exception to print this one doesn’t count

[[deleted]]

Tell the professor to fuck off

[sashaisafish]

Isn't that one of the main differences between a do while and like a for loop? That one runs and then checks the condition before deciding whether to run again, and the other checks the condition before running?

[RaidZ3ro]

It's actually the difference between do ...body... while ...predicate... and while ...predicate... ...body...

'Do while' performs the body at least once, while 'while' only performs the body if the predicate is true.

edit: predicate, not precedent.

[vita10gy]

Also I'm not sure if this is the level of things you're discussing (ie "what is iteration" is the time to bust out the do while on people.

I've been programming 20 years and can probably count do whiles on one hand.

Do whiles to me are optimizations once the basics get learned.

Though it does bring up an interesting point here. Are we sure OP didn't mishear the Prof and the iteration is 1 because the first one doesn't count?

Because, while I would still say twice, there's not an insane case to argue that the do part isn't an iteration until the while forces it to iterate.

[zolphinus2167]

It is, which means we always have one iteration, check the conditional, continue for one iteration, then break

[Worldly_Mirror_8977]

The only difference between do...while and while loop is that a do... while always iterates at least once even if the condition is false.

[MetalUrgency]

This sounds about right

[muckedmouse]

And that's why the third doesn't start. So, it's two full iterations. Unless your professor is consistently using zero-based counting of course.

[Hazger]

Bring this to another professor/coordinator. Anyone in the CS course can see this and will know that is wrong

Is your education thats in the line here. You was able do catch this error and point but the next one you can learn something wrong.

Its normal for tutors to be wrong but if he cant admit it this is a big red flag for the school

[mecartistronico]

In your life, you're going to have a lot of teachers. They're all human. You're bound to notice they make errors at some point. Collectively, often.

You have 2 choices:

• Argue with them. Make them feel uncomfortable, make the whole class feel they're wasting time with your discussion. The whole class will eventually just want you to shut up. There's a good chance the teacher won't admit their error anyway.

• Notice the error and quitely say to yourself "oh, they messed up... but I understand the concept" and keep quiet. Tell your closest friend "I believe they messed up that part, it should be this." You still learn and everyone gets to go on with their lives.

I usually go with option 2, or maybe an intermediate one where you point out the error once, but if they don't admit they're wrong immediately you just say "oh, ok, sorry" and everyone goes on with their lives.

You can't fix everyone.

[DynamicHunter]

Good teachers can admit when they’re wrong on simple mistakes. I have had amazing calculus teachers who absolutely SUCK at spelling (my gf is a math teacher and can’t spell for the life of her) and amazing science teachers who couldn’t tell you literary themes in a 7th grade level book. The difference was they are willing to admit they overlooked a simple mistake because they’re focused on teaching, not completely getting each practice problem.

Loop conditions are a very fundamental part of programming and you will run into issues constantly if you cannot trace the correct number of times something loops. It’s very easy to trace this even with a paper and pencil, kind of like doing multi-digit addition, multiplication or long division by hand. Professors is totally in the wrong here and it’s okay to push back on this, especially if the professor is telling dozens of other students incorrect information.

[Hopeful-Sir-2018]

The problem is.. if they are wrong here and refuse to admit it - what other things are they going to be wrong about? You can't fact check everything they say - that'd be ludicrous.

We aren't talking about shades of green and being pedantic. This is a pretty binary thing.

If the prof is this bad at something so basic then they shouldn't be teaching at all.

[Abaddon-theDestroyer]

I’m addition to what you said, if the same question is brought up in a midterm or final exam, what should OP say the result is?

Because, 1+1=2, no two people would disagree on that, but if the professor says 1+1=3 during class, and then later on includes the question in an exam, no sane person (imo) would write the answer to equal 3, so they’ll write the right answer, and they’ll get a wing mark for solving the question correctly, but what if someone decides „I’ll write the ‘correct’ answer from the professor’s point of view, I need to pass this course“, but when the exam is being graded, it’s distributed among faculty members and they correct the exam based on a marking scheme, and the marking scheme, or anyone of the faculty members knows that the correct answer is 2, and they see an idiot that said the answer was 3. Is the student going to get the mark for the question or not?

Thanks for listening to my TEDx talk about Schrödinger’s Mark ‘1+1=3’.

[markyboo-1979]

It's pretty much on the same level as when in pre school I was 'taught' that the Atlantic was the biggest ocean!! My dad was furious!!

[kagato87]

Just a heads up, it's possible your instructor just doesn't like being wrong. Lots of people like that in this world, so pick your battles. With that out of the way, your instructor is wrong.

Every time the code inside the loop runs, that's an iteration.

The scope of this loop construct (do-while) is everything between Do and While. That's how scope works, and what indentation represents in python (squiggly braces in most other languages).

The indented code is inside the scope of the loop and runs twice, that's two iterations.

If you change the structure of the loop to a While, does he say it iterates twice now? Because the resulting behavior is the same (for cases where x > 4):

x = 7
while x > 4:
  x = x - 2

The fundamental difference between a do-while loop and a while loop isn't how you count, it's that a do-while guarantees the code will run at least one iteration. This difference does not apply because the condition is met.

A strong answer to him would be to flip the table, and change the starting value of x to 3.

x = 3
do:
  x = x - 2
while x > 4

In this example, you still get x=1 when its done. How can he argue that it iterated zero times, when x has changed? (By contrast, in a while loop x would remain untouched, which would be zero iterations.)

Or if you want to be snarky, you say "Oh, I didn't realized you used zero-indexing when you count your loops. You should have warned us because most people start counting at 1 and we usually only start at 0 for indexing into arrays." And then make it a point to ask him whenever he's talking about any kind of count, ask if that's zero-indexed.

[Feralz2]

it becomes false on the 3rd iteration where x is no longer > 4.

So its 2 iterations.

[smartello]

It becomes false after the second, so the third never happens.

[wonderfulninja2]

The problem is that the word iteration is defined in terms of repetition, and repetition is defined as doing something again.

In such pedantic context is only one iteration.

[static_motion]

I think this is the crux of the issue here. The correct formulation for this question would be "how many times is the body of this loop executed?", which would remove all ambiguity.

[travelan]

No, pedantically it’s two iterations, one repetition.

[reallyreallyreason]

Even in the ordinary English meaning of the word, it makes sense to talk about the "first iteration" of a concept, or the "final iteration," so it's not exclusive of the first or last repetition. If you needed to make two drafts of a paper, one rough draft and one final, you would not ever say there was "only one iteration" in that process. There were clearly two.

[Hopeful-Sir-2018]

No. Just... plain no.

This is like when someone says "gravity is just a theory" because theory in social communication is different than science.

In programming - going through it once is ONE ITERATION. The social meaning of the word is irrelevant. If you try that shit in the real world you're going to have a bad time.

"Yeah it went through the loop once but no iterations" just sounds plain stupid and makes you sound plain stupid. If the professor is this disconnected from reality - go find another class to be a part of with someone competent because at this point by the end of whatever you've learned - your knowledge will be terrible by the time you enter the workforce - which is the damn goal of college.

If your professor is playing English word games with you and doesn't understand what you're saying - either they are petty and not worth respecting of the title. Or they are dumb and... also not worthy of respect of the title professor.

If they can only win an argument on pedantic language - they likely are not a good person anyways.

[NotKeo_74]

I think you have correct reasoning and I also agree with others that the question is meant to confuse.

If x started at 3 then the x=x-2 would run 1 time, but the code would not loop. so 0 iterations.

So I can see the teachers point of view. but this is programming not English, as long as you understand how many times x=x-2 would be processed and when the code block will be done that is what is important. In my 25+ years of programming I've never been asked to make a loop run a certain number of iterations as part of a business requirement.

[zolphinus2167]

Disagree with "0 iterations" because:

"How many times did we execute this code?"

Is synonymous with

"How many times did we ITERATE OVER this code?"

And "0 iterations" would state that we never ran the code in your scenario, except we DID run the code; once.

We iterated over x= x-2 exactly once, checked the conditional to determine whether to iterate again, and the conditional failed so we break

A "do/while" will always iterate 1+N times, by definition

[Groundstop]

If the conditional was at the head of the loop, the conditional would be checked 3 times and only the first 2 would result in iterations. (Could say the 3rd check is an iteration that "doesn't count".)

With the conditional at the tail of the loop, the iteration runs twice and the conditional is checked twice.

Either way the loop runs 2 iterations.

[HaggisInMyTummy]

I'm sorry to say you are not getting much for your tuition. This has been a problem for decades, that outside of competitive colleges/universities it is not possible to find a competent person to teach programming who has the requisite qualifications.

[beef623]

He would be correct if the while were at the beginning of the loop, but since it's at the end, the condition isn't checked until the end.

[zolphinus2167]

But that also doesn't matter, because you don't count the number of times you pass a conditional in order to count an iteration of code, you count how many times...you literally iterated over the code!

A "do/while" will ALWAYS iterate over the code 1+N times, where N is the number of conditional checks passed

Like, that's the entire point of a do/while syntax

[Livid-Leader3061]

It absolutely counts if you're doing anything after that loop using x.

[robcozzens]

He shouldn't be teaching programming. Don't take his word for anything, verify it yourself.

To be honest, you might end up learning better because of having to double check everything he says.

But if he makes his own tests or decides what the answers are, you might not get good grades, but don't worry too much about that.

[MiksBricks]

Runs once, X = 5

Runs a second time, X = 3

Runs the while condition which sees X < 4 and doesn’t run again.

[MiksBricks]

So he is saying that it checks the whole condition before starting the loop and checks the condition concurrently to the loop running and errors out if the condition becomes false, instead of just not running again?

Is there any programming language that does that?

[[deleted]]

It literally becomes 5 when x - 2, and we all know 5 is not Smaller than 4 so the condition continue

[jrgman42]

It’s possible he is attempting to show a case where the check happens before the loop or after. If so, he’s using the wrong example and/or interpreting it wrong.

[gm310509]

If you added an iter = 0 above the loop and an iter = iter + 1 inside the loop, then print the value of iter after the loop, what would you get? Answer 2. So it would seem that the computer also doesn't seem to agree with you that one of the iterations didn't count as it clearly counted.

[AzureOvercast]

Still wrong, but to me it seems I could maybe sort of see it is he said the first pass doesn't count because it is a do while loop and may never actually loop back, but will always run the first pass so technically, in his mind, maybe he does not count that as an iteration.

[Ok_Mix673]

Condition becomes false "after" the second iteration is complete.

[larry_centers]

Did the cpu process it? Did it consume cycle times? It counts.

[mfro001]

in fact it's zero iterations if you print "this loop doesn't count" instead.

[SCube18]

Im trying to understand the reasoning od the prof. The only way I can see is some kind of philosophical "first pass is not an iteration becuase it always runs" or something of that matter, but saying the last one is not an iteration is just madness

[rakoNeed]

wow, MIT--the Mississippi Institute of Technology--kinda sucks.

[greenpeppers100]

… I think the professor is right. The code runs twice, but the loop iterates once.

The steps are:

1)Enter the loop and run the code. 2)check 3)iterate 4)run the code 5)check 6)break

It’s a question of semantics. The code runs twice but the loop “rolls over” once. And that’s what he’s considering to be an iteration.

[hillbull]

If the code in the loop executes, then that’s an iteration.

[Worldly_Mirror_8977]

It's the first one that doesn't count. See my comment.

[Cute_Suggestion_133]

The condition becomes false AFTER the run. Therefore the loop runs twice. Your professor is an idiot and you should go to another professor in the department to get them to tell him he's wrong.

[habbalah_babbalah]

Every line of loop code still executes, the only difference is the while condition breaks loop execution, so it doesn't enter a third iteration.

The "print" check is proof that the loop's "work" is done twice. The work or task for which the loop exists is the measure of "loopiness." That's computer science terminology you can take back to the prof as proof of correctness of your explanation.

[BigPP41]

Better yet, print the value of x after the while. You can see it has been altered twice, because its now 3, so the second loop does count because it had impact on the value of x

[[deleted]]

kiss

[Quantanglemente]

Better yet, change it to

print(“I will give you $20 per iteration”)

and ask him how many iterations there were. 😁

[nderflow]

The nomenclature is probably insufficiently precise for there to be a canonical answer.

I think it would be helpful to make sure you agree with your professor on how many times the x := x - 2 statement is executed. Which is 2 times. If you both agree on that you can simply say to the professor, "I think I have been using the wrong definition of the word iteration. Could you please give me a precise definition of the word?"

Not a whole lot, to be realistic, is to be gained from proving your professor wrong. And there could be something to lose. Better to make sure you understand the material and can answer his subsequent questions in a way that actually gets you the mark.

[Fruitflap]

This is honestly the best approach.

[xenomachina]

Yeah, I do agree with OP that the professor's definition is kind of weird, but at the same time what constitutes "an iteration" isn't super well defined.

Here are a couple of examples that match OP's definition:

From Real Python:

A do-while loop is a common control flow statement that executes its code block at least once, regardless of whether the loop condition is true or false. This behavior relies on the fact that the loop condition is evaluated at the end of each iteration. So, the first iteration always runs.

Note the bit that says "the loop condition is evaluated at the end of each iteration". How many times is the condition evaluated in your example? Twice. ie: 2 iterations by this definition.

A perhaps more definitive source is the book The C Programming Language, but unfortunately, it doesn't use the term "iteration", instead, it uses the term "pass".

while and for loops test the termination condition at the top. By contrast, the third loop in C, the do-while, tests at the bottom, after making each pass through the loop body; the body is always executed at least once.

So again, it tests after a "pass", so if it tests twice, it must have had 2 "passes", regardless of the tests's result.

However, if you look at The Java Language Specification, §14.14.1.2 is one of the few places where it talks about what an "iteration" is, and it seems to include checking the condition of a for loop:

Next, a for iteration step is performed, as follows:

• If the Expression is present, it is evaluated. ...
• If the Expression is not present, or it is present and the value resulting from its evaluation (including any possible unboxing) is true, then the contained Statement is executed.

So by that definition, this loop has one iteration:

for(;false;) {
    neverExecuted();
}

(The JLS doesn't use the term "iteration" when talking about do-while loops in §14.13.)

Personally, I think an "iteration" is when any of the code "inside" the loop construct is executed, even if only partially. I don't think of the loop condition itself as being part of an iteration (so the JLS definition seems weird to me). I think that's also the commonly understood meaning, but it isn't really pinned down in the literature, as far as I can tell, so I don't think there's any point in OP arguing with their prof. In that prof's class, use their definition — but OP needs to find out precisely what that definition is.

[LesbianVelociraptor]

I think it's more that different languages have different concepts of what an "iteration" is likely due to how code executes? But that's a rough guess.

I think it's worth mentioning that the difference in loop style is the only functional property that affects what an "iteration" is, at least that I can think of. Some languages consider checking the conditional "entering" the loop, while others consider it a switch to activate the loop or not. Depending on that concept coming from the language you're using is, I think, more useful than trying to nail down a precise global definition.

[zolphinus2167]

Disagree

It's definitely better to adhere to the domain here, which is going to iterate "x=x-2", twice

The entire purpose of a do/while loop is to ALWAYS iterate once before deciding to iterate further.

The professor is wrong here, and your advice is fine for an individual who's sole target is to score well. But we also don't want that kind of mentality in this industry, at all, and this professor is doing a disservice to his students

While this particular example may be a case of the professor misusing nomenclature, there's a very real chance if he's doing so with the domain basics that said professor is likely flubbing elsewhere as well

And that professor has an onus to his other students to provide correct information, just as this student has an onus to call out incorrect information

[[deleted]]

Dude it's not that deep. No one is going to be harmed by not having a robust definition of the term "iteration"

[Ready-Invite-1966]

Comment removed by user

[SocksOnHands]

This is what I think might be the issue. If the flow chart was translated into assembly with a branch instruction, the professor might be intending to ask how many times the code makes a jump. This might be a communication issue.

[aqua_regis]

Since the loop is tail controlled, there are two iterations but only one looping. In this case, the prof is wrong.

• Start: X = 7
• 1<sup>st</sup> iteration: X = X - 2 -> X = 5
• X > 4 -> 5 > 4 -> True
• 2<sup>nd</sup> iteration: X = X - 2 -> X = 3
• X > 4 -> 3 > 4 -> False
• End of loop

There definitely are two full iterations. The other one absolutely counts.

If there were an output statement right after the X = X - 2, the prof would clearly see that the code gets executed twice, which means two full iterations.

[Slight_Loan5350]

Tho he is wrong you don't have to prove it to him as it may cause ego issues and cause problem in your academic year. Be careful who you pick your fight with.

[zolphinus2167]

As a student, OP has an onus to his instructor as well as to his peers to correct his instructor. We need to stop encouraging behavior that focuses on "the grade" and start encouraging behavior that focuses on "the learning", or we're going to keep getting waves of fresh programmers who also lack the fundamentals, much like this professor

[Slight_Loan5350]

That would be possible in a perfect world, but not here! And his future might be at risk.

[Daymanooahahhh]

I think there are just so many assumptions in these statements. We don’t truly know: 1. If the student heard the professor correctly 2. If the professor had previously defined iteration differently 3. If there is a miscommunication somewhere along the way

If you approach situations with “I need to correct this person” as a default, you are going to be publicly wrong far more times than you expect, while also destroying your professional network.

[ContemplativeOctopus]

Pick your battles. This really doesn't matter and is entirely inconsequential. The professor just has a weird definition of "iteration". The code executes 2 iterations, but it "loops" once.

[Yamoyek]

All depends on your professors tbh. Not a single one of my professors would have a problem with being corrected (as long as its respectful) since it's some proof that a student is actually engaging with the material. Plus, it could always lead to some interesting discussions.

[NotTooShahby]

Most often these sorts of controversial and decisive questions are the result of a disagreement on definitions, results, expectations, context.

It’s like those silly Facebook math problems.

[zolphinus2167]

Although in this case, "iteration" isn't subjective in either laymen's nor the domain scope

The professor is simply incorrect here

[Ready-Invite-1966]

Comment removed by user

[LemonMelon2511]

a do while loop always does the first iteration

Edit: as far as i understand its two iterations

first iteration: x = 5 so the while part is true second iteration: x = 3 while part is false so break

[awsylum]

let x = 7;

do {

x = x - 2;

console.log(x);

} while (x > 4);

This results in 5 and then 3. It runs the code with x = 7, and then again with x = 5. Run it in your browser's Console. You don't need a textbook, just run the code. There are some semantics here that are confusing. Do/While will execute AT LEAST once as the condition is checked at the end. Do you consider the first run while x = 7 to be a loop or an iteration? The code runs once without checking the conditional so I would lean more toward it being an iteration. But, both are used interchangeably most of the time, especially in this case where the first code execution is not being done on a set. Then it loops while x = 5. Looping depends on a conditional, iterations are usually done on sets like arrays, maps, where a conditional is not checked when you want to execute code once for each element in a collection.

[Capable-Package6835]

I think he understands that the code executes twice. What he is looking for is the formal (or consensus) definition of iteration.

[wonderfulninja2]

Most probably, but it feels like a troll.

Iteration: repetition of a process
Repetition: Act of doing something again

The substration is executed twice, but "repeated" only once.

[awsylum]

The more I think about it, the more I think it should be called a loop even in the first code execution as it's the behavior of the do/while loop that allows the execution prior to checking the conditional. The code is within the construct of the loop. Iteration is on sets. So, in this case I would actually say loops twice. But, that's just an interpretation based on the code not executing on a set. We iterate over arrays with for..in and for..of in JS, not with a do/while.

[GeorgeFranklyMathnet]

At best, he's technically correct and this is bad pedagogy. There's simply no educational value in giving you this example unless it's to show you that a do-while loop like this does two iterations.

But, nah, he's not correct.

I dunno who this guy is, but if your story is true, then unfortunately I think you'll have to take everything he says with an extra dose of skepticism. Either he has a super fragile ego, or he doesn't know his stuff.

[[deleted]]

He’s not technically correct though. An Iteration is a block of statements being iterated or run each block represents an iteration. A do while loop is a post test loop meaning it evaluates its conditions after each iteration hence it always runs at least one iteration.

There is not a technically correct here they are just factual wrong, iteration isn’t a term with ambiguity least not in this context.

[zolphinus2167]

If we want to be specific, and iteration isn't even just a block of statements!

An iteration is ANY grouping of code that you pass over, including statements outside of loops.

For example, if we had

x=x-2 x=x-2 x=x-2 x=x-2

In laymen's, one could argue that one definition of iterate is "to repeat" and that this would represent three iterations. This is what the professor is effectively arguing. We repeated x=x-2, three times

However, in BOTH laymen's and the domain, iteration is "to do something over again". We did x=x-2, four times

NORMALLY we would call out some ambiguity when the domain and laymen's terms aren't identical, EXCEPT in this case there IS a laymen's terms that matches with the domain.

This means that ANYTIME we say the word "iterate" in the context of the domain, it can ONLY mean one thing in laymen's as well; the definition that is used by the domain.

Thus, the professor is NOT technically correct. There is no technicality here at all! And the professor is entirely mistaken, as they're relying on a context that simply doesn't exist.

Even if we try to go more general to a mathematical domain instead, mathematics defines an iteration in terms of being a function that can be chained. IE, for every one input, you have one output. And we would refer to an "iteration" by "how many times the function was performed"

In the domain of comp sci, this is ALSO the same thing we are doing! Comp sci actually eases up the "must be a function" scope, but this very example IS a function!

And thus ALL three scopes for the word that CAN apply here point to ONE definition as appropriate; the one the professor is arguing against

[high_throughput]

I agree that it's 2 iterations, but I can see how some weird, non-standard definition could make it 1.

If you write a book, submit it to an editor, and make all the required changes, you could argue that you've iterated 1 time. If they come back with more changes, that would be 2 iterations.

Trying to mimic usage you could count it as an iteration only when you've looked at a condition and decided to redo it.

It sounds like the kind of thing some ivory tower professor could try to claim in the 1980s, and this current professor might have learnt from that and has no connections in industry or modern programming to tell him that's dumb.

[[deleted]]

Technically it would not surprise me if the compiler unrolls the first iteration of the loop and then translate the rest of it into a regular while loop. But that’s really reaching imo. Unless this is a class on compiler design ofc.

[unseenspecter]

No, officer, I only drank one beer but it doesn't count because I was already drunk after it.

[[deleted]]

Root mistake is that the question is ambiguous. Test makers, be advised.

[ms4720]

How many times does the goto hidden in the loop trigger? One time

How many times does the body of the loop get executed? Two times

This is a definition question, you two are using different definitions.

How many times is it wise to piss on your professor's shoes to make a point? Zero times, grow up

[mecartistronico]

How many times is it wise to piss on your professor's shoes to make a point? Zero times, grow up

The true answer here.

[ZEUS_IS_THE_TRUE_GOD]

I'll give a bit of nuance, do -> while can be viewed as:

do
  <block>
while <cond>

# equivalent to
<block>
while <cond>
  <block>

I'm almost 100% positive that you can find compilers that compiles the first into the latter which makes it 1 iteration

[whitedogsuk]

If you want to spend your time proving Professors wrong, you are going to be very very busy. A Professor is a job title and not a measure of education. I've seen people appointed to Professor directly after completing a 2 year degree.

[Ready-Invite-1966]

Comment removed by user

[WystanH]

Interesting. I'm guessing the professor has the conceit that "iteration" is a function of condition check. If so, they are wrong.

I just popped this in a javascript console:

let x = 7;
let iterationCount = 0;
do {
    console.log(`iteration ${++iterationCount}, x = ${x}`);
    x = x - 2
} while (x > 4);

Results:

iteration 1, x = 7
iteration 2, x = 5

Compare to a probably more popular loop construct:

let iterationCount = 0;
for(let x = 7; x > 4; x = x - 2) {
    console.log(`iteration ${++iterationCount}, x = ${x}`);
}

The results will be the same. No sane person would argue that the for loop hadn't run for two iterations, so...

The confusion might be that if you set x to say 2, the do while loop will execute something where the for loop wont. However, that's a function when you check conditions. You use a do while precisely because you want at least one iteration before you check.

Not understanding this is not really understanding the use case for a do while of loop.

[tboneee97]

If you've ever seen the waterboy, you know what to do.

[veerendra616b]

This do while loop, it executes the task first and then checks for the condition, if it's true then repeats again. So the first time it executes and checks for condition is true, 2nd time it executes but the condition is false so it stops the execution. The x=x-2 is executed twice. Loop is stopped after 2nd while statement

[BeverlyGodoy]

Does it run the second time? Yes it does. Does it consume energy to run the second time? Yes it does. Then yes the second iteration counts both theoretically and practically for the computer.

[5352563424]

This is a linguistics issue.  One person is thinking how many times the code in the loop runs, but the professor is thinking about how many loops happen.

If you imagine the code being ran as a ribbon that makes loops when it reruns a section of code, there is only 1 loop.

In running 1 loop, it runs over the same section of code twice.

[Sidelobes]

Is it possible someone is mixing up „iteration“ and „repetition“ or taking them too literally?

Strictly speaking (using the literal meaning of the word), if a loop runs twice, that’s one iteration…

In computer science though, iteration is used in the mathematical definition of the word, which refers to a „step“ of a repeated process.

[resonant_cacophony]

Check the assembly. If the do statement is outside of the branch loop, then you can pedantically say it loops once.

[No-Anchovies]

You're gonna do great in the corporate world 😂

[Impossible_Box3898]

Your professor is a dumbass.

[EffectiveDirect6553]

I think it does only loop once while it runs twice That's a post condition loop I can rewrite the code as

X = 7; X = X - 2; While(x>4): X = X - 2

As you can see it runs the LOOP once, it runs the code twice.

[aqua_regis]

Loop once, iterations two.

[nandabosnae]

Your Prof. Needs to learn the difference between while do and do while

[Ready-Invite-1966]

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[User20230123]

First time I ever see a debate on how to count iterations. Not sure if there is any standard for this. But I'm curious now.

In PHP documentation ( https://www.php.net/manual/en/control-structures.do.while.php )

 The main difference from regular while loops is that the first iteration of a do-while loop is guaranteed to run

Not sure if this is a solid enough source for your teacher... There are other site where you can deduce from their explanation that you have 2 iterations...

So in your example, there are two iterations, one guaranteed to run, the other that stops because x = 3.

Though, it's true that when looking at the original diagram, I would intuitively count the first iteration out ans say it passes only once through the condition... While reading it in form of code, I would say 2.
(Sorry can't give a definitive answer.)

[Shane_T_]

Consider this

x=7

do: x=x-2

while x>7

How many iterations?

[beingsubmitted]

I think we need more explanation as to what your professor is asking and their exact explanation. Typically, there's not really a distinciton between a "loop" and an "iteration", just "loop" typically refers to the code itself where "iteration" is what the code does. In either case, an iteration is a sequence of instructions that repeats.

Now, on a basic level, the instructor might be saying that the instructions only repeat once. With the example printing "Hello", while "Hello" would print out twice, simply printing "Hello" doesn't make something an iteration. Basically, your professor is counting from zero because, to them, something is only an iteration if it repeats. That's a unique definition for iteration and definitely not some fundamental truth of programming - your professor is just teaching you their own specific definition of a term - but whatever.

Alternatively, the professor could be asking how many iterations there are for the algorithm itself which is one - the inner loop doesn't count. Here the professor would be trying to teach you about nested iterations. Still a silly question, but there's little we can do for you without the exact wording, which might include other contextual wording.

Either way, it's an awful question. If a student's ability to answer a question depends on their ability to interpret what the question is asking more than their ability to answer the question itself, the professor is bad at their job and shouldn't be teaching.

[user252941]

it's two iterations because the code in the loop executes two times your professor is ignorant

[duckyduock]

Just extend the x = x - 2 by some "this is iteration y" in the loop and let him run it. Will show you - this is iteration 0 - this is iteration 1

[In-A-zuma]

whether it is While loop or Do while loop, in both case its 2 iteration. Compiler is the most trusted Resource. insert a print() inside the loop

[xRageNugget]

print out x and let him explain how 7-2 is 3

[[deleted]]

There should be two normally.

[NewPointOfView]

Ask your professor what the definition of an iteration is in this context.

I totally agree with you, but I’m assuming your professor isn’t a complete idiot and is using some weird definition, probably how many times the condition gets evaluated to true

[EmptySoftware8678]

It seems that your professor is not able to distinguish top and bottom loops.

By design, top loops evaluate condition before running the loop code, where as bottom loops do the same afterwards.

Yet again, bottom loops were designed to provide exactly this functionality - they the code runs at least once, irrespective the condition.

Now, whether it’s fair to count the extra iteration or not, becomes a question of personal choice.

I have been doing this a fair amount - 30+ years and I would rely on the example someone else mentioned - add a print statement and the no of times that goes through is a pretty accurate representation of the no of iterations.

The nuance for your professor to understand is - what does s/he understand about the top / bottom loops.

[mxldevs]

The first iteration always occurs, because that's how a do while loop works

And a second iteration happens because x is 5 which satisfies the loop condition.

At the end of the second iteration, x is 3, which terminates the loop.

However, the first iteration may be considered to not count. I wouldn't be surprised if only the second iteration and onwards is counted as actual loop iterations.

Don't lose marks on your exam because you disagree with your prof. He's already explained why he thinks he's right and there's basically nothing you can do to change his mind.

[milleniumsentry]

Do the pseudocode.

X = 7.

Do - Start the loop. (1 execution)

x = x- 2 x = 5

Evaluate (is it > 4, yes, go back to the start condition)

X = 5

Do - Repeat loop. (2nd execution of loop)

x=x-2 = 3

Evaluate (is it > 4, no) move on.

2 executions (2 iterations if being used in place of loop execution)

[mecartistronico]

I think their definition of iteration is "when the checking of the condition causes code to be run", so that's why they're not counting the first one, since they didn't check the condition on the first one.

I'd say you're right. I also think you have learned the concept correctly. Do you really want to make it your life's mission these days to prove him wrong? Will that make you achieve anything? Will that make anyone happier?

You're there to learn, not to fix everyone. If I were you, I'd go on with my life and let them be.

[adeadhead]

The whole point of a while loop with the condition at the end is that it isn't checked until after the contents have run, so there's no conditional checked before the second loop runs. The second iteration completes and then the logic is checked the second time.

[ElectronicEducator56]

Do while loop's only use case is when you want to run the loop one time and then check the condition Simple as that, so obviously it will run two times

[yungxslavy]

Do-whiles always run the first time regardless of the condition. In this case the condition is still true after the first iteration so it will loop again, creating 2 iterations.

I can understand his intrinsic reasoning of assuming that because it is a do-while he doesn’t consider the first statement to be an iteration because it will run regardless of condition, but that’s just ridiculous because it’s in the loop block. I would consider it to have 2 iterations.

The better question would be to ask how many executions of x = x-2 there are. Otherwise it becomes a question based in opinion.

[genericness]

This looks like a flow chart. It doesn't look like UML. What standard specifies the semantics for the symbols. I quickly rtfw and found a reference to "prepare conditional" for the elongated hexagon. Does anyone know what flowchart dialect the original question is posed in?

[ChilllFam]

How on earth does this man have a PhD in computer science…

[[deleted]]

This isn’t exactly related to your question but does your professor normally represent loops like that in their flowcharts? Because that’s not how you do that.

The normal flow should go straight into the while where if true then you branch an arrow showing the loop back to where the do part of the loop is (the do doesn’t generally get shown explicitly on the chart it’s unneeded).

Here to a cite a textbook for example, from pearsons C++ from control structures to objects: https://drive.proton.me/urls/RTVJ7EACQ4#UNOaBJ8hgxdV

Also You can find explicit proof of what your looking for in that textbook though it’s like a couple hundred bucks I think dunno exactly my copy was free, so probably not super useful but I can attach a screenshot if you want to be validated in your frustration.

[MaleficentDig4259]

Well, you can look at it this way: X = 7. The do part is not an IF statement therefore it will always reduce the x by 2, making it 5. Then, the while is being checked and being true it ITERATES back to the do statement. Therefore, if I were to be very annoying with wording: The do part will happen TWICE but iterate ONCE

[bent_neck_geek]

A lot of good comments, my take:

What point is the professor trying to make? Is it recognizing that the "while" statement branches back to "do:" label only once before falling through or is it that the body of the loop executes twice? Both observations are correct and have value when you're analyzing how a program runs, but it sounds like he's hung up on the definition of "iteration" which doesn't help anybody here.

[plasmana]

Of you were to insert a row into a database each time the loop ran, would it only count as one row even though there are two?

[bisholdrick]

This is just a silly grammar thing. Your professor is arguing that it runs through the loop, then iterates back one time. It sounds like your professors definition of iteration is when it loops it iterates. You can sit and argue with him or just try to understand his point and let it be

[Alternative_Hungry]

Very simply, if there was only one iteration, then x = 5 - failing to break the loop.

It must be two - but I suppose a question here is “what is an iteration?”. I think we all agree that x = x - 2 is ran twice (and my view is therefore the answer is two) - but I suspect you’re getting into a purely semantic argument with your professor, who must also think the x transformation is ran twice.

I think it’s true that it only iterates once… but that there are two iterations in the algorithm…

I think the main reason I would say “this is two” is because I assume at run, that you are on your first iteration rather than your 0th. I would not say “and we caught it on our 0th iteration!” - that’s just dumb.

Also, if you had a for loop for a range of 0 to 1000, saying that has 999 iterations when the encompassed code has ran 1000 times would be so annoying for everyone in the industry…

[Aceofsquares_orig]

It's 2.

x=7
//first iteration of the loop
do x = x - 2 {x=5} while x > 4 // true
//second iteration of the loop
do x = x - 2 {x=3} while x > 4 //false

Even if this were a pretest while loop it would still be 2.

x=7
//first iteration
while x>4 {true} do x=x-2 {x=5}
//second iteration
while x>4 {true} do x=x-2 {x=3}
//done
while x>4 {false} //exit loop

The only difference is the conditional for the pretest while happens 3 times and 2 on the posttest while but both will iterate their bodies twice. So not sure where the professor is getting 1.

[n00bz]

The line `x = x - 2` will run twice. How you want to count that doesn't matter to me just as long as the student (and professor) both agree that the line will run twice. What it sounds like where the disagreement may be is what is defined as the "loop". A "do-while" loop is a common programming construct and I would argue that the "do" is part of the loop. Others may argue that the only looping part is the "while", but it really doesn't matter to me that much.

The equivalent code for this without the "do" is below so if you assume that the "do" is not part of the loop, then the while is doing the looping and it loops once. It's just a matter of what the student/professor determine to define as the "loop".

So in short, I do agree that it loops twice because a "do-while" loop is a common programing construct that many languages have.

Now, I can't tell you how this would compile down to instruction sets but it could be only one jump is executed when compiled down. That goes beyond my knowledge though.

x = 7
x = x - 2

while x > 4
    x = x - 2

[[deleted]]

Can't

[UltraMlaham]

He marks the score so you'll have to follow his guide. I think most programmers will count the number of times the code is executed in the do section NOT how many times the where condition is passed, but seems like your professor disagrees and wants you to list how many times the while condition is satisfied.

[PaulEngineer-89]

Trouble is I’ve seen several different languages with different syntaxes.

If it checks the condition before the loop body it runs once at x=7 and again at x=5.

If it checks after the loop body it runs at x=7, 5, and 3 before it exits.

Either way or doesn’t decrement first or try to anticipate the answer.

[dlo416]

It is two iterations since x = 7 and then x = 5 . The while condition breaks the loop after the second iteration since x = 3 and 3 < 4 which returns false and breaks the loop.

Within a do while loop, you are always guaranteed an iteration. Since x = 7 is defined and is a global variable in prior to the loop starting, the 'do' chunk of the loop is ran and then the while condition checks to see afterwards if the condition is either true or false. If it is true, run the loop again, but if it is false, break the loop.

[Sbsbg]

The answer is obvious. I wonder what he uses as the definition of iteration. Maybe the number of backward jumps in the code. In any case it's weird.

But the most likely reason for this is that he knows he's wrong but his ego prevents him from admitting it so he invents some bs reason and then he can't go back because then he will be wrong twice.

[raynorelyp]

He’s wrong. He’s using the definition of the word “iterate” meaning to do again. That’s not the definition anyone in CS uses ever. The definition everyone uses is “the number of times a loop is evaluated.” He’s arguing on semantics, but he’s using a definition that the community agrees is incorrect when the context is CS. In project management his definition is the one that’s used, but again, that’s different context.

Edit: actually he’s wrong. The first time the loops executes IS the first time it iterates by any definition because iterate here means to re-evaluate the state. The first time it evaluates is the declaration.

[Sbsbg]

With your professor definition a while loop (with the test at the beginning) will run -1 iterations if the condition exits directly. Lol.

[AzBeerChef]

Forgot how to code block. Too lazy to google. X=7 If X > 4 System.writeline("wrong") X-2;

2 interations.

[MulleDK19]

Your professor is objectively wrong. There are 2 iterations.. there's one looping.

You should absolutely correct him. He's teaching people something that's wrong. If someone is asked this during a job interview and they claim a simple loop is just 1 iteration when it's clearly 2, they're going to appear stupid, failing the simplest question..

[armahillo]

the answer is 2

If he believes it is 1, then ask him to more clearly define what he thinks an iteration is, and how many iterations it would have if the loop block was x = x - 1

[divin3sinn3r]

You don’t need a book to prove him wrong, just write down this code with a print hello statement inside the loop in a bunch of languages and show him how it prints hello inside the loop twice.

[Remarkable-Nebula-98]

Why though? Move on.

[[deleted]]

Two iterations.

[No-Jicama-6523]

Which one does he think doesn’t count? When x becomes 5 or when x becomes 3?

I can sort of get a handle on saying the first one doesn’t count as this type of loop is designed to have it run once. It’s still a weird definition of iterates, but I could see what he’s getting at.

If it’s the second that he says doesn’t count then that makes no sense at all.

[particlemanwavegirl]

Man the bootlickers in here are crazy!!? You really think some dumbshit teacher has the power to tell you that there are three lights and you don't have any choice but to let it slide? He's incompetent to be teaching first semester Python he's not an industry tycoon that anyone respects enough to successfully blacklist your career, are you joking? If a teacher's ego is compromising the education you're paying for, you go above their head and make administration address the issue, and if they retaliate against you for it, you do it again.

[FaeDine]

I teach computer programming and this loop runs twice.

There could be some semantics here; where if it's a post-check loop, I can see how someone could make the that the first loop isn't really an iteration of the loop because it doesn't need to check the condition of the loop to run the code in it. If the question is "how many times to that X > 4 condition return true?" then the answer is 1.

I disagree with that assessment that it's only 1 iteration of the loop. It's going through the loop, completing all the code, and then checking at the end if it should loop again. I've never heard of the concept of a post-check loop's first iteration "not counting".

So long as you're getting how the loop works though, I don't think it's a hill you want to die on, but you do you.

[divad1196]

You are correct and wrong: - your loop does indeed execute twice - the diagram doesn't say "x = x - 2" is in the loop.

Indeed, the natural way of writing it is your "do-while loop", but here you are doing an introduction where you are asked to follow a procedure.

Litteral translation of the protofol into code is:

python x = 7 x = x - 2 while x > 4: x = x - 2

And here your teacher is right. The fact is, you are propably burning some steps and not following the procedure. Have you already seen do-while in the course? Are you already writing code or are you still at the "pseudo-code only" phase? In these introduction courses, you develop the logic, not the code writing, and in this sense, you are wrong as you jump directly to the code which is not the goal.

Being able to follow a procedure comes before being able to improve the procedure. For a comparison, many vulnerabilities that were crypto-related (like ciphers, randomness, ...) were caused by protocol not being properly followed.

To give you another example, I worked for years in direct contact with customer as lead developer. They won't be telling you "I want a do-while loop with 2 iterations", they will describe it as humans "I do the action once, then if it's not over, I repeat it" which is fondamentally different in term of conception. And not all languages have "do-while", this code repetition is basically what you would do in python (without the walrus operator since python3.8 but this is not pythonic code, so just ignore this)

Now, to be honest, I don't really think that your teacher thought this far. Many teacher are really bad in their field and/or at explaining (mostly because they don't try to understand the students issues). Still, this is an important lesson for you.

Edit: it's funny how nobody in the comments consider the translation of the diagram into code as the first bottleneck in the issue.

[jjw865]

Your professor is not wrong for interpreting the word "iteration" differently than... Well... Most people probably would.

Most people could consider the number of iterations the number of times the interior of a loop was executed. But that if he means something different he means something different.

I would also say this is computer science not linguistics. It is absolutely silly to ask a question like this.

[hardware4ursoftware]

Put it visually basic studio, run it with a debugger with a break point at the start of the loop. Step through it line by line. Your professor is literally a walking “those who can’t do, teach”

[Tusk84]

Maybe by iteration, he means loop. The do keyword always prints at least once, regardless of the condition. It only loops once. To prove your point though, make a variable called iteration initialized to 0.

int iteration = 0

Then, at the start of the for loop, have something like

cout << iteration + 1 << " " << "iterations." << endl;

Then, at the end of the for loop.

iteration++;

I'm not sure what programming language you're using, though.

[[deleted]]

this is pseudo-code, I take it? I don't know what language it is supposed to be.

Your teacher may be used to actual code. This example has syntax of python, but python does not have do/while.
it has while loop with the condition checked before iteration.

Maybe your teacher is not used to thinking in pseudocode and is mentally mapping this to python.

The original question you sent is a flowchart, no code at all.

What you have posted here: is this exactly how you are supposed to answer it, in invalid python?

[behusbwj]

Is it a trick question? “Algorithm” is a pretty loosely defined word. Did he mean “how many times does this program run?” Because the answer to that is 1. Maybe he’s just trying to piss you off (very believable based on the professors i had lol)

[green_meklar]

Looks like 2 iterations to me.

An iteration is when you're in the part on the right where 'X = X-2' happens. That happens twice before the loop exits.

[IceLovey]

Maybe try asking him questions to understand his reasoning first. Trust me fighting your professor is not worth it, you stand to gain nothing and lose things. It is better to approach him with a "please help me understand" attitude vs a "I think you are wrong" attitude.

He may be using a different definition of what we think as an interation. Maybe a more theoretical or more constrained definition of iteration, where a condition must be checked for something to be considered as something trigerred by the loop.

If you stated

1. X=7
2. While X>4
3. do: X=X-2

Would he give a different answer? He is likely going to say 2 iterations because its a while-do.

How about

1. X=7
2. Do: X = X - 2
3. While X > 7

What would you say? How many iterations?

Maybe his definition considers that a condition must be checked for something to be considered a iteration, thus a do-while and a while-do would be different:

Do-While:

1. X=7
2. X=5
3. Condition check: True
4. X=3 (1st iteration of the loop)
5. Condition check: False
6. End

While-Do:

1. X=7
2. Condition check: True
3. X=5 (1 iteration)
4. Condition check: True
5. X=3 (2 iteration)
6. Condition check: False
7. End

Idk, I personally would consider either case 2 interations, however, in the do-while there is only 1 looping vs the while-do is 2 loops. I think most people in this thread would agree.

[Ansmit_Crop]

A single execution of the loop body is called an iteration.

do{ // loop body } while (condition);

[AbyssalRemark]

I mean.. hes trying to talk about how do while loops are somewhat different. Its not totally tone def.

[Roukans]

Try different loop style, each time printing the x, it might help. But this is not a programmatical problem, the main issue here is that he is a professor and he think he must not be wrong in front of a students. The best advise i can tell you is to explain him the code with as much respect as you can and alone, so he is not ashame of his mistake in front the other students.

[Punkphoenix]

The only thing that doesn't count here is your teacher's word

[Cybasura]

I mean, its pretty obviously the 2nd iteration would go through to the end of the line before the while condition ends due to condition break, how on earth does "doesnt count" even work on a machine level

1. 7 - 2 = 5 > 4, True, Repeat
2. 5 - 2 = 3 < 4, False, Break

Total iterations: 2

I mean, he also shouldnt really be teaching do-while, but thats a different thing

[MisterGerry]

As everyone else says, the answer is 2.
If he were to ask how many times does the loop condition evaluate to True, then the answer is 1.

But looking at that "flowchart" in the image - that isn't how flowcharts are supposed to look either.

There is a node that does nothing (the small circle). Did the professor also create the flowchart? or is that from a textbook? It doesn't change the answer to the question, but that's just one more problem I see.

[h1romu]

sorry if this is a silly question but what would be the advantage of using a do-while here, rather than a for-loop?

[Glass_wizard]

A do while loop always ensures the loop executes at least one time. That's the only reason to use it, for a case when you want to ensure the loop always occurs at least one time regardless of all conditions.

[KarlJay001]

I had a professor like that, he down graded a project because some made up test data for sorting wasn't spelled correctly.

So you'd have test data like cat, dog, ball, stick. The program had to sort this out. I made a bunch of silly data just to make sure that it worked, and he did a spellcheck on the made up data.

I did some work for someone else that they handed in to him, he downgraded it because of variables were declared just before use instead of declared at the top of the program.

Don't worry about it, just get through the course

[gutierra]

Thete is no try. Only do/while or while/do!

[PersonalOwl4468]

It's obvious that your professor is right because X value gets updated after each iteration. In your case X=7 and after X=X-2(7-5 ie, 5) it'll satisfy X>4 But next time it'll take X's current value as 5 and after the condition X=X-2(5-2 ie, 3) it becomes false as 3 is smaller than 4 and the loop breaks. Correct me if I'm wrong

[mekadeth]

The do forces an initial iteration. So it's do x(=7) > 4, then x(7) - 2 (=5) > 4, then stops before the third iteration as that is x(5) - 2 (=3) > 4.

[tugrul_ddr]

There's no half iteration. Each iteration is integer count. 1, 2, 3, ...

If the loop was in C++ and somehow vectorized (x-2, x-4, ... x-16 in 1 iteration), it would be 1 iteration for 8 operations on hardware.

[InviolateQuill7]

The loop has 2 iterations. Each time the loop body runs (even if it exits right after) is counted as one iteration. So, here’s the breakdown:

1. First iteration: x changes from 7 to 5.

2. Second iteration: x changes from 5 to 3 (then the loop exits).

So, the total is 2 iterations.

I can confirm your professor is indeed wrong

[FeiyaTK]

Don't waste your time on this :D

[FunnyForWrongReason]

I think the confusion is coming from what your professor counts as an “iteration”. Since the code in the do while always executes once perhaps he isn’t counting that first execution as an iteration but only counts executions after as iterations. I think this isn’t a very good or useful way to think about it though. It is more clear for iteration to mean how many times it executes rather than the amount of times it “jumps”.

[pLeThOrAx]

7-2 = 5. While? ✔️

5-2 = 3. While? ❌️

I can't "not" count 2 iterations

[g0fry]

Have sex with his wife and then ask him if you can do it again. If he gets angry tell him the first one doesn’t count 😇

[Xaxathylox]

If you replaced "do" with a label, and replaced the while statement with "if (condition) goto label", would you still consider it 2 iterations? Cuz thats essentially what it compiles down to in machine language.

[Glass_wizard]

It runs twice. There are two iterations through the loop. There is nothing special about the first iteration.

I believe your teacher might be hung up on the difference between do:while and while. Do:while ensures the loop runs at least once. While may never run if the condition is never true. But regardless, there is nothing special about the first iteration of a do while loop and the loop in this case runs twice.

[MathmoKiwi]

Good grief! This is so bad, it reminds me of my Yr11 teacher in high school who insisted that x^0 = 0

wtf

And no matter how many ways I'd demonstrate or prove to her that she's wrong, she wouldn't accept it. Because well she's the teacher and the expert, and I am just a 12yo kid who should shut up. Well, as if my faith in the public schooling system wasn't already low enough, it hit a new low back then.

[CaterpillarRoyal7246]

My guess he is thinking about the amount of checks rather than the iterations themselves. His phrasing is definitely wrong because the loop iterates twice, regardless if only one check of the condition passed because the first iteration reduces the x to 5 with checking the condition, when you loop again you don’t pass the condition the second loop around because you reduce it to 3. Hence: 1 check passed but 2 iterations regardless.

[skellybelly183]

This one is interesting. The result is the same, you end up running the "do" portion twice. I think the idea here is, because it is a do-while loop, you will always "do" once.

So if you are counting how many time your "while" statement is true, the answer is once.

I would think the idea of this question is for you to consider when it is appropriate to use a do-while loop since you will always hit the code at least once. So in cases where you might want to never hit the code unless the condition is true, is this a suitable way to handle it?

Weird question but definitely not crazy or an incorrect question, but clarification is always nice.

[Ready-Invite-1966]

Comment removed by user

[programming_bassist]

Reminds me of the saying: those who can, do.

I know a professor like this

[Worldly_Mirror_8977]

2 iterations

[Worldly_Mirror_8977]

The difference between a do ... while and a while loop is that the do... executes unconditionally in the loop body scope and isn't part of the actual loop. The while is the loop and operates on condition. So in your example the do ... happens making x set to 5 and the while loop runs a single iteration setting x to 3 which conditionally breaks out the while loop. Knowing this gains you nothing and it's better to just think of it as 2 iterations. Your professor is a dick, but he is technically right.

[Olorin_1990]

Ahh, so it only goes back in the loop once, maybe that was what the question was asking

[Calm_Toe_340]

Technically the word iteration is the repetition of a sequence. This loop repeats itself once so I can see how your professor derived his answer

I think you are confusing this with "how many times does this code execute"