C# 0 The Complete Reference

A Closer Look at select

The

select

 clause determines what type of elements are obtained by a query. Its general 

form is shown here:

select

expression

So far we have been using 

select

 to return the range variable. Thus, 

expression

 has simply 

named the range variable. However, 

select

 is not limited to this simple action. It can return 

a specific portion of the range variable, the result of applying some operation or transformation 

to the range variable, or even a new type of object that is constructed from pieces of the 

information retrieved from the range variable. This is called 

projecting.

To begin examining the other capabilities of 

select

, consider the following program. It 

displays the square roots of the positive values contained in an array of 

double

 values.

// Use select to return the square root of all positive values

// in an array of doubles.

using System;

using System.Linq;

class SelectDemo {

  static void Main() {

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