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Source Code

The LinqOverArrayUsingEnumerable project can be found under the Chapter 14 subdirectory.

Investigating the C# LINQ Query Operators

C# defines a good number of query operators out of the box. Table 14-3 documents some of the

more commonly used query operators.

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Note

The .NET Framework 3.5 SDK documentation provides full details regarding each of the C# LINQ opera-

tors. Look up the topic “LINQ General Programming Guide” for more information.

Table 14-3.

Various LINQ Query Operators

Query Operators

Meaning in Life

from, in

Used to define the backbone for any LINQ expression, which

allows you to extract a subset of data from a fitting container.

where

Used to define a restriction for which items to extract from a

container.

select

Used to select a sequence from the container.

join, on, equals, into

Performs joins based on specified key. Remember, these “joins”

do not need to have anything to do with data in a relational

database.

orderby, ascending, descending

Allows the resulting subset to be ordered in ascending or

descending order.

group, by

Yields a subset with data grouped by a specified value.

In addition to the partial list of operators shown in Table 14-3, the Enumerable type provides a

set of methods that do not have a direct C# query operator shorthand notation, but are instead

exposed as extension methods. These generic methods can be called to transform a result set in var-

ious manners (Reverse<>(), ToArray<>(), ToList<>(), etc.). Some are used to extract singletons

from a result set, others perform various set operations (Distinct<>(), Union<>(), Intersect<>(),

etc.), and still others aggregate results (Count<>(), Sum<>(), Min<>(), Max<>(), etc.).

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