C# 0 The Complete Reference

PART I

C h a p t e r   1 9 :  

L I N Q  

581

PART IPART I

of a query in an array. 

ToList( )

 returns the results of a query in the form of a 

List

 collection. 

(See Chapter 24 for a discussion of collections.) In both cases, the query is executed to obtain 

the results. For example, the following sequence obtains an array of the results generated by 

the

posNums

 query just shown. It then displays the results.

int[] pnums = posNum.ToArray(); // query executes here

foreach(int i in pnums)

  Console.Write(i + " ");

}

Expression Trees

Another new LINQ-related feature is the 

expression tree.

 An expression tree is a representation 

of a lambda expression as data. Thus, an expression tree, itself, cannot be executed. It can, 

however, be converted into an executable form. Expression trees are encapsulated by the