In cases where you want to resolve the set to a single item and manipulate that item, but still gracefully handle situations where that item may not be found in the set, you can can delay the FirstOrDefault
until the very end, like this:
var reversed = testList
.Where(x => x == "hello")
.Select(x => x.Reverse())
.FirstOrDefault();
Or equivalently
var reversed = testList
.Where(x => x == "hello")
.Select(Enumerable.Reverse)
.FirstOrDefault();
This will return null
if no items are in the list that satisfy the condition specified in the Where
method. The performance difference here will be at most negligible. It won't require looping through the testList
any more than the original code, since once the first element is found, the result is immediately returned.