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ArrayIndex Method (Expression, Expression[])

Expression.ArrayIndex Method (Expression, Expression())

Creates a MethodCallExpression that represents applying an array index operator to a multidimensional array.

Namespace:  System.Linq.Expressions
Assemblies:   System.Core (in System.Core.dll)
  System.Linq.Expressions (in System.Linq.Expressions.dll)

'Declaration
Public Shared Function ArrayIndex ( _
	array As Expression, _
	ParamArray indexes As Expression() _
) As MethodCallExpression

Parameters

array
Type: System.Linq.Expressions.Expression

An array of Expression instances - indexes for the array index operation.

indexes
Type: System.Linq.Expressions.Expression()

An array of Expression objects to use to populate the Arguments collection.

Return Value

Type: System.Linq.Expressions.MethodCallExpression
A MethodCallExpression that has the NodeType property equal to Call and the Object and Arguments properties set to the specified values.

ExceptionCondition
ArgumentNullException

array or indexes is Nothing.

ArgumentException

array.Type does not represent an array type.

-or-

The rank of array.Type does not match the number of elements in indexes.

-or-

The Type property of one or more elements of indexes does not represent the Int32 type.

Each element of indexes must have Type equal to Int32. The Type property of array must represent an array type whose rank matches the number of elements in indexes.

If the rank of array.Type is 1, this method returns a BinaryExpression. The Left property is set to array and the Right property is set to the single element of indexes. The Type property of the BinaryExpression represents the element type of array.Type.

If the rank of array.Type is more than one, this method returns a MethodCallExpression. The Method property is set to the MethodInfo that describes the public instance method Get on the type represented by the Type property of array.

The following example demonstrates how to use the ArrayIndex(Expression, Expression()) method to create a MethodCallExpression that represents indexing into a two-dimensional array.

Dim gradeArray(,) As String = _
    {{"chemistry", "history", "mathematics"}, {"78", "61", "82"}}

Dim arrayExpression As System.Linq.Expressions.Expression = _
    System.Linq.Expressions.Expression.Constant(gradeArray)

' Create a MethodCallExpression that represents indexing 
' into the two-dimensional array 'gradeArray' at (0, 2). 
' Executing the expression would return "mathematics". 
Dim methodCallExpression As System.Linq.Expressions.MethodCallExpression = _
    System.Linq.Expressions.Expression.ArrayIndex( _
        arrayExpression, _
        System.Linq.Expressions.Expression.Constant(0), _
        System.Linq.Expressions.Expression.Constant(2))

Console.WriteLine(methodCallExpression.ToString())

' This code produces the following output: 

' value(System.String[,]).Get(0, 2)

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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