Article
11/18/2011

Expression.NewArrayInit Method (Type, IEnumerable<Expression>)

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Creates a NewArrayExpression that represents creating a one-dimensional array and initializing it from a list of elements.

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

Syntax

'Declaration
Public Shared Function NewArrayInit ( _
    type As Type, _
    initializers As IEnumerable(Of Expression) _
) As NewArrayExpression

public static NewArrayExpression NewArrayInit(
    Type type,
    IEnumerable<Expression> initializers
)

Parameters

type
Type: System.Type
A Type that represents the element type of the array.

initializers
Type: System.Collections.Generic.IEnumerable<Expression>
An IEnumerable<T> that contains Expression objects to use to populate the Expressions collection.

Return Value

Type: System.Linq.Expressions.NewArrayExpression
A NewArrayExpression that has the NodeType property equal to NewArrayInit and the Expressions property set to the specified value.

Exceptions

Exception	Condition
ArgumentNullException	type or initializers is nulla null reference (Nothing in Visual Basic). -or- An element of initializers is nulla null reference (Nothing in Visual Basic).
InvalidOperationException	The Type property of an element of initializers represents a type that is not assignable to the type that type represents.

ArgumentNullException

type or initializers is nulla null reference (Nothing in Visual Basic).

-or-

An element of initializers is nulla null reference (Nothing in Visual Basic).

InvalidOperationException

The Type property of an element of initializers represents a type that is not assignable to the type that type represents.

Remarks

The Type property of each element of initializers must represent a type that is assignable to the type represented by type, possibly after it is quoted.

Note:
An element will be quoted only if type is Expression. Quoting means the element is wrapped in a Quote node. The resulting node is a UnaryExpression whose Operand property is the element of initializers.

The Type property of the resulting NewArrayExpression represents an array type whose rank is 1 and whose element type is type.

Examples

The following example demonstrates how to use the NewArrayInit method to create an expression tree that represents creating a one-dimensional string array that is initialized with a list of string expressions.

Dim trees As New System.Collections.Generic.List(Of System.Linq.Expressions.Expression) _
        (New System.Linq.Expressions.Expression() _
         {System.Linq.Expressions.Expression.Constant("oak"), _
          System.Linq.Expressions.Expression.Constant("fir"), _
          System.Linq.Expressions.Expression.Constant("spruce"), _
          System.Linq.Expressions.Expression.Constant("alder")})

' Create an expression tree that represents creating and  
' initializing a one-dimensional array of type string.
Dim newArrayExpression As System.Linq.Expressions.NewArrayExpression = _
    System.Linq.Expressions.Expression.NewArrayInit(Type.GetType("System.String"), trees)

' Output the string representation of the Expression.
outputBlock.Text &= newArrayExpression.ToString() & vbCrLf

' This code produces the following output:
'
' new [] {"oak", "fir", "spruce", "alder"}

List<System.Linq.Expressions.Expression> trees =
    new List<System.Linq.Expressions.Expression>()
           { System.Linq.Expressions.Expression.Constant("oak"),
             System.Linq.Expressions.Expression.Constant("fir"),
             System.Linq.Expressions.Expression.Constant("spruce"),
             System.Linq.Expressions.Expression.Constant("alder") };

// Create an expression tree that represents creating and  
// initializing a one-dimensional array of type string.
System.Linq.Expressions.NewArrayExpression newArrayExpression =
    System.Linq.Expressions.Expression.NewArrayInit(typeof(string), trees);

// Output the string representation of the Expression.
outputBlock.Text += newArrayExpression.ToString() + "\n";

// This code produces the following output:
//
// new [] {"oak", "fir", "spruce", "alder"}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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