Possible purpose of LINQ select( x => x )

Question

I'm going through some LINQ examples from a book on MVC and I'm wondering what purpose the select call below could have. Maybe it's a typo but I don't see any mention of it in the book's errata.

foreach( Product p in products
    .Where( e => e.Name == productParam.Name )
    .Select( e => e ) ) {
        p.Price = productParam.Price;
}

I tested out two examples of this where the .Select( e => e) was included and one where it was not and the code is the same. Since Where returns the IEnumerable filtered by the predicate then when would the select call (with the specific predicate above) ever be necessary? Does it actually do anything? Could it in some weird corner case?

Answer 1

It would return the exact same thing as without it, an IEnumerable<T>. It's actually doing more harm than good though as it's performing a redundant O(n) operation (looping through the whole list).

References

• MSDN - Enumerable.Select
• MSDN - Enumerable.Where

Answer 2

Does it actually do anything?

It does add overhead to the entire operation. In reality, it should be removed, as it serves no useful purpose.