The original code runs through the numbers 0-59 very very fast. Thousands of times per second. The Arduino can easily count to 60 in less than 1 millisecond.
Then once a second the timer expires and whatever LED it's pointing to gets checked. That will be basically random.
What is wrong with gfvalvo's code? Does it do something like you expect?
Thanks for the input MorganS, I think I understand now, gfvalvo's code works perfectly, I just wanted to understand where I had gone wrong for future reference.
If I understand correctly, you would typically use a delay at the end of the for loop to control the timing of the for loop.
I have instead tried to use millis to control the timing (incorrectly). Is it possible to use millis to control the timing of a for loop, how would you go about this? or is there a different method to control the timing of a for loop (other than delay)?
Thanks