loop increment

Question

How to convert a for with a increment to Parallel.For?

for (int i = 0; i < n; i += block)
{
...
}

Answer 1

The only way I know to do this is to make an enumerable, then use Parallel.ForEach:

IEnumerable<int> ForLoopBlock(int start, int end, int incr)
{
    for (int i=start; i<end; i+=incr)
       yield return i;
}

Then, you can do:

Parallel.ForEach (this.ForLoopBlock(0,n,block), (i) => { ... });

---

Reed Copsey, Jr. - http://reedcopsey.com

Answer 2

You could also do something like this:

public static void ParallelFor(

    int fromInclusive, int toExclusive, int step, Action<int> body)

{

    ... // validate parameters here

    if (step == 1)

    {

        Parallel.For(fromInclusive, toExclusive, body);

    }

    else // step > 1

    {

        int len = (int)Math.Ceiling(

            (toExclusive - fromInclusive) / (double)step);

        Parallel.For(0, len, i => body(fromInclusive + (i * step)));

    }

}