Question

I have the following linq query:

 var files = (from d in new DirectoryInfo(@"c:\program files").GetDirectories()
                         where d.GetFiles().Count() > 10
                         where d.GetFiles().Count() < 100
                         select d
             );

However, as you can see above, I am calling d.GetFiles().Count() twice, is this where the concept of the => operator comes in handy.

Using the syntax from jdehaan, why can’t I do it directly like this:

var files = (from d in new DirectoryInfo(@"c:\program files").GetDirectories()
                         where(x => x.GetFiles().Count() > 10) &&
                         (x.GetFiles().Count() < 100))
                         select d
             );

I know the above is stupid because I could just do my original query with d.GetFiles().Count(), but I am curious on the difference between using Where as opposed to the keyword where.

Answer 1

Use let to assign within the query, like this

var files = (from d in new DirectoryInfo(@"c:\program files").GetDirectories()
   let f = d.GetFiles().Count()
   where f > 10
   where f < 100
   select d
);

As Reed Copsey points out you can merge the two where clauses using &&.

Also, since GetFiles returns an array you can use the Length property instead of the Count method.

  var files = (from d in new DirectoryInfo(@"c:\program files").GetDirectories()
     let f = d.GetFiles().Length
     where f > 10 && f < 100
     select d
  );