Professional LINQ

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Scott Klein

"Professional LINQ"

Aggregate(Enumerable.Empty(),
(current, next) => next.Length > 2 ? current.Union(next) : current);
71
Part I: Introduction to Project LINQ
foreach (string item in namelist)
listBox1.Items.Add(item);
When this query is run, the following results are returned because two of the arrays have more than two
elements:
Joe
John
Jim
Josh
Joyce
Dave
Dinesh
Doug
Doyle
Change the query so that it is looking for arrays that have more than five elements, as shown below:
IEnumerable namelist = names.Aggregate(Enumerable.Empty(),
(current, next) => next.Length > 5 ? current.Union(next) : current);
When the query is run now, nothing is returned. Or better said, an empty collection is returned. You can
tell this by placing a breakpoint on the foreach statement. When the query is run, the execution does
indeed step into the foreach statement, letting you know that an empty collection was returned, but the
line that adds items to the list box is not hit or executed.
The Empty operator is basically used as a seed value for the aggregate operator if the criteria is not met.

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An Account of the Customs and Manners of the Micmakis and Maricheets Savage Nations, Now Dependent on the Government of Cape-Breton (page 110) Danny's Own Story (page 224) Mrs. Falchion, Volume 2. (page 52)

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Scott Klein

"Professional LINQ"