Menu
I believe (from some research reading) that counting down in for-loops is actually more efficient and faster in runtime. My full software code is C++
I currently have this:
for (i=0; i<domain; ++i) {
my 'i' is unsigned resgister int, also 'domain' is unsigned int
in the for-loop i is used for going through an array, e.g.
array[i] = do stuff
converting this to count down messes up the expected/correct output of my routine.
I can imagine the answer being quite trivial, but I can't get my head round it.
UPDATE: 'do stuff' does not depend on previous or later iteration. The calculations within the for-loop are independant for that iteration of i. (I hope that makes sense).
UPDATE: To achieve a runtime speedup with my for-loop, do I count down and if so remove the unsigned part when delcaring my int, or what other method?
Please help.
404
Using the reversed() function to count down in a for loop in Python. The reversed() function takes a sequence and reverses its order. We can create a simple sequence using the range() function and reverse it using this function. After reversing the sequence, we can iterate over it using the for loop to count down.
A: Always, count Down to Zero loops are better.
There is only one correct method of looping backwards using an unsigned counter:
for( i = n; i-- > 0; )
{
// Use i as normal here
}
There's a trick here, for the last loop iteration you will have i = 1 at the top of the loop, i-- > 0 passes because 1 > 0, then i = 0 in the loop body. On the next iteration i-- > 0 fails because i == 0, so it doesn't matter that the postfix decrement rolled over the counter.
Very non obvious I know.
188
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
