6 ms·

Running from 0 to -6 is 7 iterations. Running from 0 to INT_MIN is |INT_MIN| + 1 iterations.

Thorrez 6y ago
>Running from 0 to -6 is 7 iterations. I guess it depends on your definition of an iteration. I view an iteration as including the iteration expression (i-- in this case) at the end. So during 7 iterations, i-- has executed 7 times, so the value of i is -7. You seem to be saying the iteration expression belongs to the next iteration as opposed to belonging to the currently ending iteration. I think my view is the widely accepted view. Check out how cppreference rewrites a for loop: { init_statement while ( condition ) { statement iteration_expression ; } } In our specific case: { i = 0; while (i < 6) { printf("."); i--; } } https://en.cppreference.com/w/cpp/language/for https://en.cppreference.com/w/cpp/language/for Also the article doesn't say "running |INT_MIN| + 1 iterations" it says "after |INT_MIN| + 1 iterations". I think in that case, even if you don't consider the final i-- to be part of the "n + 1 iterations", you would still consider the final i-- to be done "after |INT_MIN| + 1 iterations".
- susam 6y ago
  >> Running from 0 to -6 is 7 iterations. > I view an iteration as including the iteration expression (i-- in this case) at the end. Then you should agree that running from 0 to -6 (inclusive) is 7 iterations. Example: #include <stdio.h> int main() { int i; for (i = 0; i >= -6; i--, printf("iterated\n")) { printf("i = %d\n", i); } return 0; } Output: i = 0 iterated i = -1 iterated i = -2 iterated i = -3 iterated i = -4 iterated i = -5 iterated i = -6 iterated
  - jonsen 6y ago
    7 times through the loop is 6 iterations. It’s the first time that is iterated, repeated.
    - susam 6y ago
      Isn't the first pass through the body of the loop also often colloquially called "the first iteration"?
      - jonsen 6y ago
        Yes, but look at your example here. The value is decremented to -6 after the 6. iteration, right? That’s what Thorrez is saying at the start of this thread.
        susam 6y ago
        Thank you for elaborating the terminology issue in your comments. I do see Thorrez's point now. If we consider an iteration to be complete when i-- (the iteration expression) has been completed execution, then yes, the value of the variable i is decremented to -6 when the 6th iteration completes. In fact, the value of the variable i is decremented to -7 when the 7th iteration completes. The language used in this blog post regarding the iterations (which is also quoted by Thorrez) is indeed sloppy. I will update it soon and fix it. Thank you, jonsen and Thorrez, for paying attention to the details!
  - deleted 6y ago
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- user-the-name 6y ago
  The body of the loop will run |INT_MIN| + 1 times. I don't think there is a more well-accepted definition of "iteration" than that.
  - jonsen 6y ago
    > ...well-accepted definition of "iteration"... To say or perform again; repeat. synonym: repeat. To utter or do again; repeat: as, to iterate an advice or a demand. Repeated. So x+1 times is x iterations.
    - user-the-name 6y ago
      I don't think I have ever heard a programmer say that running a piece of code two times is "one iteration".
      - jonsen 6y ago
        But they can say both of: - From 1 to 10 there is 9 - From 1 to 10 there is 10 How far from 0 to INT_MIN - it depends.
        user-the-name 6y ago
        None of that affects the fact that if a loop runs 10 times, all programmers will say that it ran for 10 iterations.
        jonsen 6y ago
        Yes. My point here is that Thorrez at the start of this thread may have a point: Start 0 1. iteration -1 2. iteration -2 3. iteration -3 ... at the end of the |INT_MIN|’th iteration INT_MIN
    - wruza 6y ago
      You may define or argue that it is, but it's not a common sense for anyone.

>Running from 0 to -6 is 7 iterations. I guess it depends on your definition of an iteration. I view an iteration as including the iteration expression (i-- in this case) at the end. So during 7 iterations, i-- has executed 7 times, so the value of i is -7. You seem to be saying the iteration expression belongs to the next iteration as opposed to belonging to the currently ending iteration. I think my view is the widely accepted view. Check out how cppreference rewrites a for loop: { init_statement while ( condition ) { statement iteration_expression ; } } In our specific case: { i = 0; while (i < 6) { printf("."); i--; } } https://en.cppreference.com/w/cpp/language/for https://en.cppreference.com/w/cpp/language/for Also the article doesn't say "running |INT_MIN| + 1 iterations" it says "after |INT_MIN| + 1 iterations". I think in that case, even if you don't consider the final i-- to be part of the "n + 1 iterations", you would still consider the final i-- to be done "after |INT_MIN| + 1 iterations".

susam 6y ago
>> Running from 0 to -6 is 7 iterations. > I view an iteration as including the iteration expression (i-- in this case) at the end. Then you should agree that running from 0 to -6 (inclusive) is 7 iterations. Example: #include <stdio.h> int main() { int i; for (i = 0; i >= -6; i--, printf("iterated\n")) { printf("i = %d\n", i); } return 0; } Output: i = 0 iterated i = -1 iterated i = -2 iterated i = -3 iterated i = -4 iterated i = -5 iterated i = -6 iterated
- jonsen 6y ago
  7 times through the loop is 6 iterations. It’s the first time that is iterated, repeated.
  - susam 6y ago
    Isn't the first pass through the body of the loop also often colloquially called "the first iteration"?
    - jonsen 6y ago
      Yes, but look at your example here. The value is decremented to -6 after the 6. iteration, right? That’s what Thorrez is saying at the start of this thread.
      - susam 6y ago
        Thank you for elaborating the terminology issue in your comments. I do see Thorrez's point now. If we consider an iteration to be complete when i-- (the iteration expression) has been completed execution, then yes, the value of the variable i is decremented to -6 when the 6th iteration completes. In fact, the value of the variable i is decremented to -7 when the 7th iteration completes. The language used in this blog post regarding the iterations (which is also quoted by Thorrez) is indeed sloppy. I will update it soon and fix it. Thank you, jonsen and Thorrez, for paying attention to the details!
- deleted 6y ago
  [deleted]
user-the-name 6y ago
The body of the loop will run |INT_MIN| + 1 times. I don't think there is a more well-accepted definition of "iteration" than that.
- jonsen 6y ago
  > ...well-accepted definition of "iteration"... To say or perform again; repeat. synonym: repeat. To utter or do again; repeat: as, to iterate an advice or a demand. Repeated. So x+1 times is x iterations.
  - user-the-name 6y ago
    I don't think I have ever heard a programmer say that running a piece of code two times is "one iteration".
    - jonsen 6y ago
      But they can say both of: - From 1 to 10 there is 9 - From 1 to 10 there is 10 How far from 0 to INT_MIN - it depends.
      - user-the-name 6y ago
        None of that affects the fact that if a loop runs 10 times, all programmers will say that it ran for 10 iterations.
        jonsen 6y ago
        Yes. My point here is that Thorrez at the start of this thread may have a point: Start 0 1. iteration -1 2. iteration -2 3. iteration -3 ... at the end of the |INT_MIN|’th iteration INT_MIN
  - wruza 6y ago
    You may define or argue that it is, but it's not a common sense for anyone.