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Queryable.Select(TSource, TResult) Method (IQueryable(TSource), Expression(Func(TSource, Int32, TResult)))

Projects each element of a sequence into a new form by incorporating the element's index.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

JScript does not support generic types or methods.

Type Parameters

TSource

The type of the elements of source.

TResult

The type of the value returned by the function represented by selector.

Parameters

source
Type: System.Linq.IQueryable(TSource)

A sequence of values to project.

selector
Type: System.Linq.Expressions.Expression(Func(TSource, Int32, TResult))

A projection function to apply to each element.

Return Value

Type: System.Linq.IQueryable(TResult)
An IQueryable(T) whose elements are the result of invoking a projection function on each element of source.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(TSource). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source or selector is a null reference (Nothing in Visual Basic).

This method has at least one parameter of type Expression(TDelegate) whose type argument is one of the Func(T, TResult) types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression(TDelegate).

The Select(TSource, TResult)(IQueryable(TSource), Expression(Func(TSource, Int32, TResult))) method generates a MethodCallExpression that represents calling Select(TSource, TResult)(IQueryable(TSource), Expression(Func(TSource, Int32, TResult))) itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Select(TSource, TResult)(IQueryable(TSource), Expression(Func(TSource, Int32, TResult))) depend on the implementation of the type of the source parameter. The expected behavior is that it invokes selector on each element of source to project it into a different form.

The following code example demonstrates how to use Select(TSource, TResult)(IQueryable(TSource), Expression(Func(TSource, Int32, TResult))) to project over a sequence of values and use the index of each element in the projected form.

No code example is currently available or this language may not be supported.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5

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