Expression.Assign(Expression, Expression) Method

Definition

Namespace:

System.Linq.Expressions

Assemblies:

netstandard.dll, System.Linq.Expressions.dll

Source:

BinaryExpression.cs

Creates a BinaryExpression that represents an assignment operation.

C#

public static System.Linq.Expressions.BinaryExpression Assign(System.Linq.Expressions.Expression left, System.Linq.Expressions.Expression right);

Parameters

left

Expression

An Expression to set the Left property equal to.

right

Expression

An Expression to set the Right property equal to.

Returns

BinaryExpression

A BinaryExpression that has the NodeType property equal to Assign and the Left and Right properties set to the specified values.

Examples

The following code example shows how to create an expression that represents an assignment operation.

C#

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

// To demonstrate the assignment operation, we create a variable.
ParameterExpression variableExpr = Expression.Variable(typeof(String), "sampleVar");

// This expression represents the assignment of a value
// to a variable expression.
// It copies a value for value types, and
// copies a reference for reference types.
Expression assignExpr = Expression.Assign(
    variableExpr,
    Expression.Constant("Hello World!")
    );

// The block expression allows for executing several expressions sequentually.
// In this block, we pass the variable expression as a parameter,
// and then assign this parameter a value in the assign expression.
Expression blockExpr = Expression.Block(
    new ParameterExpression[] { variableExpr },
    assignExpr
    );

// Print out the assign expression.
Console.WriteLine(assignExpr.ToString());

// The following statement first creates an expression tree,
// then compiles it, and then executes it.
Console.WriteLine(Expression.Lambda<Func<String>>(blockExpr).Compile()());

// This code example produces the following output:
//
// (sampleVar = "Hello World!")
// Hello World!

Remarks

The Assign expression copies a value for value types, and it copies a reference for reference types.

Applies to