Why doesn't this for loop process the full data set?

Question

Background

I have a spreadsheet of ticket allocations for an event. On each row of the spreadsheet is a name and the number of tickets allocated.

Answer 1

The compiler interperets the 'For' Loop construct differently, and uses different assembly calls to place the temporary variable into CPU cache, so after each iteration it doesn't need to go back out to RAM to read the variable, it can just grab it from the cpu's cache. This is by design to increase performance, thats why 'For' loops are generally faster than 'While' loops. The limit variable for the 'for' loop still lives in memory, but its not reading it during each iteration. So if you change the variable used to originally set the upper bound, your loop will still run to the original bound you set it to. While loops check its exit clause at each iteration, and does not cache is variable. Generally 'For' loops should be used when you have a set amount of iterations, as opposed to the while loop when you are not sure how many times you will need to loop, and need more dynamic control.