Admit it, we’ve all done it before, writing those nasty nested loops just so we can iterate through multiple lists to get some combination/permutation of the lists, e.g.:
1: for (int i = 0; i < 10; i++)
2: {
3: for (int j = 0; j < 10; j++)
4: {
5: for (int k = 0; k < 10; k++)
6: {
7: // do something
8: }
9: }
10: }
This code obviously works and well understood amongst developers, but it’s not very readable and trying to terminate the outer loops from the inner loops is a pain and requires you to use one or more boolean flags which you need to track on every iteration at potentially every level of your loop…
A better way to solve this common problem is to use LINQ to ‘flatten’ the nested loops into a single loop:
1: var triplets = from I in Enumerable.Range(0, 10)
2: from J in Enumerable.Range(0, 10)
3: from K in Enumerable.Range(0, 10)
4: select new { I, J, K };
5:
6: foreach (var triplet in triplets)
7: {
8: // do something
9: }
Sweet, right? :-)
How do you use these I J and K variables?
@Anonymous — if you mean inside the foreach loop, you will be able to reference them like triplet.I, triplet.J and triplet.K.
In the LINQ query, you can reference the variables I, J and K directly, for example:
from I in Enumerable.Range(0, 10)
from J in Enumerable.Range(0, 10)
from K in Enumerable.Range(0, 10)
select new { Sum = I + J + K }