Thread: how to come out of double loop

Originally Posted by dwks

Setting the loop control variables to their upper bounds seems like a bad idea to me though. First, it might require more maintenance, especially if the "this/that" boundary expressions are complicated. And a compiler optimizer which would otherwise see a perfect loop with nicely striding loop variables could get confused by your meddling with the control variables. You might get less optimized code as a result.

It was just an example of not needing extra values.

It would probably be better to set them to size -1 so that when the loop increments the final time before the check, that you don't overflow (in the event you are using _MAX or something). It's not really something I see myself using anyway, but you could.

Honestly, I can't see your compiler ever doing what you are suggesting. There is nothing wrong with setting the value of a loop control variable to something different inside the loop. I have never heard of that being an issue - and it shouldn't. I can't possibly imagine a scenario where that (you setting a loop control value specifically) caused your compiler to break your loop.


Quzah.

Originally Posted by quzah

Honestly, I can't see your compiler ever doing what you are suggesting. There is nothing wrong with setting the value of a loop control variable to something different inside the loop. I have never heard of that being an issue - and it shouldn't. I can't possibly imagine a scenario where that (you setting a loop control value specifically) caused your compiler to break your loop.

I wasn't thinking the compiler would break the loop, just that it would be less able to perform optimizations. Actually I was thinking of vectorization operations which usually require a countable loop . . . but using "break" to end a loop makes the loop uncountable just as surely as setting the loop index variable. So I guess my thinking wasn't very straight. You're probably right.

Originally Posted by dwks

I wasn't thinking the compiler would break the loop, just that it would be less able to perform optimizations.

Ok, I will blame the confusion on not enough coffee. I confused myself for a bit I think with "break;-ing from a loop" with "you broke the loop!".


Quzah.