Expression.ArrayAccess Methode

public:
 static System::Linq::Expressions::IndexExpression ^ ArrayAccess(System::Linq::Expressions::Expression ^ array, System::Collections::Generic::IEnumerable<System::Linq::Expressions::Expression ^> ^ indexes);

public static System.Linq.Expressions.IndexExpression ArrayAccess(System.Linq.Expressions.Expression array, System.Collections.Generic.IEnumerable<System.Linq.Expressions.Expression> indexes);

static member ArrayAccess : System.Linq.Expressions.Expression * seq<System.Linq.Expressions.Expression> -> System.Linq.Expressions.IndexExpression

Public Shared Function ArrayAccess (array As Expression, indexes As IEnumerable(Of Expression)) As IndexExpression

Parameter

Gibt zurück

Die erstellte IndexExpression.

Beispiele

Im folgenden Codebeispiel wird gezeigt, wie der Wert eines Elements in einem mehrdimensionalen Array mithilfe der ArrayAccess Methode geändert wird.

// Add the following directive to your file:
// using System.Linq.Expressions;

// This parameter expression represents a variable that will hold the two-dimensional array.
ParameterExpression arrayExpr = Expression.Parameter(typeof(int[,]), "Array");

// This parameter expression represents a first array index.
ParameterExpression firstIndexExpr = Expression.Parameter(typeof(int), "FirstIndex");
// This parameter expression represents a second array index.
ParameterExpression secondIndexExpr = Expression.Parameter(typeof(int), "SecondIndex");

// The list of indexes.
List<Expression> indexes = new List<Expression> { firstIndexExpr, secondIndexExpr };

// This parameter represents the value that will be added to a corresponding array element.
ParameterExpression valueExpr = Expression.Parameter(typeof(int), "Value");

// This expression represents an access operation to a multidimensional array.
// It can be used for assigning to, or reading from, an array element.
Expression arrayAccessExpr = Expression.ArrayAccess(
    arrayExpr,
    indexes
);

// This lambda expression assigns a value provided to it to a specified array element.
// The array, the index of the array element, and the value to be added to the element
// are parameters of the lambda expression.
Expression<Func<int[,], int, int, int, int>> lambdaExpr =
    Expression.Lambda<Func<int[,], int, int, int, int>>(
        Expression.Assign(arrayAccessExpr, Expression.Add(arrayAccessExpr, valueExpr)),
        arrayExpr,
        firstIndexExpr,
        secondIndexExpr,
        valueExpr
);

// Print out expressions.
Console.WriteLine("Array Access Expression:");
Console.WriteLine(arrayAccessExpr.ToString());

Console.WriteLine("Lambda Expression:");
Console.WriteLine(lambdaExpr.ToString());

Console.WriteLine("The result of executing the lambda expression:");

// The following statement first creates an expression tree,
// then compiles it, and then executes it.
// Parameters passed to the Invoke method are passed to the lambda expression.
int[,] sampleArray = { {10,  20,   30},
                       {100, 200, 300}};
Console.WriteLine(lambdaExpr.Compile().Invoke(sampleArray, 1, 1, 5));

// This code example produces the following output:
//
// Array Access Expression:
// Array[FirstIndex, SecondIndex]

// Lambda Expression:
// (Array, FirstIndex, SecondIndex Value) =>
// (Array[FirstIndex, SecondIndex] = (Array[FirstIndex, SecondIndex] + Value))

// The result of executing the lambda expression:
// 205

' Add the following directive to your file:
' Imports System.Linq.Expressions  

' This parameter expression represents a variable that will hold the two-dimensional array.
Dim arrayExpr As ParameterExpression = Expression.Parameter(GetType(Integer(,)), "Array")

' This parameter expression represents a first array index.            
Dim firstIndexExpr As ParameterExpression = Expression.Parameter(GetType(Integer), "FirstIndex")
' This parameter expression represents a second array index.            
Dim secondIndexExpr As ParameterExpression = Expression.Parameter(GetType(Integer), "SecondIndex")

' The list of indexes.
Dim indexes As List(Of Expression) = New List(Of Expression) From
    {firstIndexExpr, secondIndexExpr}

' This parameter represents the value that will be added to a corresponding array element.
Dim valueExpr As ParameterExpression = Expression.Parameter(GetType(Integer), "Value")

' This expression represents an access operation to a multidimensional array.
' It can be used for assigning to, or reading from, an array element.
Dim arrayAccessExpr As Expression = Expression.ArrayAccess(
    arrayExpr,
    indexes
)

' This lambda expression assigns a value provided to it to a specified array element.
' The array, the index of the array element, and the value to be added to the element
' are parameters of the lambda expression.
Dim lambdaExpr As Expression(Of Func(Of Integer(,), Integer, Integer, Integer, Integer)) =
    Expression.Lambda(Of Func(Of Integer(,), Integer, Integer, Integer, Integer))(
        Expression.Assign(arrayAccessExpr, Expression.Add(arrayAccessExpr, valueExpr)),
        arrayExpr,
        firstIndexExpr,
        secondIndexExpr,
        valueExpr
)

' Print expressions.
Console.WriteLine("Array Access Expression:")
Console.WriteLine(arrayAccessExpr.ToString())

Console.WriteLine("Lambda Expression:")
Console.WriteLine(lambdaExpr.ToString())

Console.WriteLine("The result of executing the lambda expression:")

' The following statement first creates an expression tree,
' then compiles it, and then executes it.
' Parameters passed to the Invoke method are passed to the lambda expression.
Dim sampleArray = {{10, 20, 30},
                       {100, 200, 300}}
Console.WriteLine(lambdaExpr.Compile().Invoke(sampleArray, 1, 1, 5))

' This code example produces the following output:
'
' Array Access Expression:
' Array[FirstIndex, SecondIndex]

' Lambda Expression:
' (Array, FirstIndex, SecondIndex Value) => 
' (Array[FirstIndex, SecondIndex] = (Array[FirstIndex, SecondIndex] + Value))

' The result of executing the lambda expression:
' 205

Hinweise

Der Ausdruck, der das Array darstellt, kann mithilfe der MakeMemberAccess Methode oder durch oder durch NewArrayBoundsNewArrayInitabgerufen werden.

public:
 static System::Linq::Expressions::IndexExpression ^ ArrayAccess(System::Linq::Expressions::Expression ^ array, ... cli::array <System::Linq::Expressions::Expression ^> ^ indexes);

public static System.Linq.Expressions.IndexExpression ArrayAccess(System.Linq.Expressions.Expression array, params System.Linq.Expressions.Expression[] indexes);

static member ArrayAccess : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression[] -> System.Linq.Expressions.IndexExpression

Public Shared Function ArrayAccess (array As Expression, ParamArray indexes As Expression()) As IndexExpression

Parameter

Gibt zurück

Die erstellte IndexExpression.

Beispiele

Das folgende Codebeispiel zeigt, wie sie einen Wert eines Arrayelements mithilfe der ArrayAccess Methode ändern.

// Add the following directive to your file:
// using System.Linq.Expressions;

// This parameter expression represents a variable that will hold the array.
ParameterExpression arrayExpr = Expression.Parameter(typeof(int[]), "Array");

// This parameter expression represents an array index.
ParameterExpression indexExpr = Expression.Parameter(typeof(int), "Index");

// This parameter represents the value that will be added to a corresponding array element.
ParameterExpression valueExpr = Expression.Parameter(typeof(int), "Value");

// This expression represents an array access operation.
// It can be used for assigning to, or reading from, an array element.
Expression arrayAccessExpr = Expression.ArrayAccess(
    arrayExpr,
    indexExpr
);

// This lambda expression assigns a value provided to it to a specified array element.
// The array, the index of the array element, and the value to be added to the element
// are parameters of the lambda expression.
Expression<Func<int[], int, int, int>> lambdaExpr = Expression.Lambda<Func<int[], int, int, int>>(
    Expression.Assign(arrayAccessExpr, Expression.Add(arrayAccessExpr, valueExpr)),
    arrayExpr,
    indexExpr,
    valueExpr
);

// Print out expressions.
Console.WriteLine("Array Access Expression:");
Console.WriteLine(arrayAccessExpr.ToString());

Console.WriteLine("Lambda Expression:");
Console.WriteLine(lambdaExpr.ToString());

Console.WriteLine("The result of executing the lambda expression:");

// The following statement first creates an expression tree,
// then compiles it, and then executes it.
// Parameters passed to the Invoke method are passed to the lambda expression.
Console.WriteLine(lambdaExpr.Compile().Invoke(new int[] { 10, 20, 30 }, 0, 5));

// This code example produces the following output:
//
// Array Access Expression:
// Array[Index]

// Lambda Expression:
// (Array, Index, Value) => (Array[Index] = (Array[Index] + Value))

// The result of executing the lambda expression:
// 15

' Add the following directive to your file:
' Imports System.Linq.Expressions  

' This parameter expression represents a variable that will hold the array.
Dim arrayExpr As ParameterExpression = Expression.Parameter(GetType(Integer()), "Array")

' This parameter expression represents an array index.
' For multidimensional arrays, you can define several indexes. 
Dim indexExpr As ParameterExpression = Expression.Parameter(GetType(Integer), "Index")

' This parameter represents the value that will be added to a corresponding array element.
Dim valueExpr As ParameterExpression = Expression.Parameter(GetType(Integer), "Value")

' This expression represents an array access operation.
' It can be used for assigning to, or reading from, an array element.
Dim arrayAccessExpr As Expression = Expression.ArrayAccess(
    arrayExpr,
    indexExpr
)

' This lambda expression assigns a value provided to it to a specified array element.
' The array, the index of the array element, and the value to be added to the element
' are parameters of the lambda expression.
Dim lambdaExpr As Expression(Of Func(Of Integer(), Integer, Integer, Integer)) =
    Expression.Lambda(Of Func(Of Integer(), Integer, Integer, Integer))(
        Expression.Assign(arrayAccessExpr, Expression.Add(arrayAccessExpr, valueExpr)),
    arrayExpr,
    indexExpr,
    valueExpr
  )

' Print expressions.
Console.WriteLine("Array Access Expression:")
Console.WriteLine(arrayAccessExpr.ToString())

Console.WriteLine("Lambda Expression:")
Console.WriteLine(lambdaExpr.ToString())

Console.WriteLine("The result of executing the lambda expression:")

' The following statement first creates an expression tree,
' then compiles it, and then executes it.
' Parameters passed to the Invoke method are passed to the lambda expression.
Console.WriteLine(lambdaExpr.Compile().Invoke(New Integer() {10, 20, 30}, 0, 5))

' This code example produces the following output:
'
' Array Access Expression:
' Array[Index]

' Lambda Expression:
' (Array, Index, Value) => (Array[Index] = (Array[Index] + Value))

' The result of executing the lambda expression:
' 15

Hinweise

Der Ausdruck, der das Array darstellt, kann mithilfe der MakeMemberAccess Methode oder durch oder durch NewArrayBoundsNewArrayInitabgerufen werden.

Verwenden Sie für mehrdimensionale Arrays die ArrayAccess Methode.