Question

Logically, one would think that the foreach loop in C# would evaluate in the same order as an incrementing for loop. Experimentally, it does. However, there appears to be no such confirmation on the MSDN site.

Is it simply such an apparent answer that they did not think to include that information on the site? Or is there the possibility that it will behave erratically?

Answer 1

For arrays (note that System.Array implements IEnumerable), it will access elements in order. For other types (IEnumerable, or having GetEnumerator), it accesses elements in the order provided, through alternating MoveNext and Current calls.

The standard states (ECMA-334 §13.9.5):

“The order in which foreach traverses
the elements of an array, is as
follows: For single-dimensional arrays
elements are traversed in increasing
index order, starting with index 0 and
ending with index Length – 1. For
multi-dimensional arrays, elements are
traversed such that the indices of the
rightmost dimension are increased
first, then the next left dimension,
and so on to the left.”