This documentation is archived and is not being maintained.

Expression.Parameter Method (Type)

Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.

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

public static ParameterExpression Parameter(
	Type type


Type: System.Type
The type of the parameter or variable.

Return Value

Type: System.Linq.Expressions.ParameterExpression
A ParameterExpression node with the specified name and type.

The following example demonstrates how to create a MethodCallExpression object that prints the value of a ParameterExpression object.

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

// Creating a parameter for the expression tree.
ParameterExpression param = Expression.Parameter(typeof(int));

// Creating an expression for the method call and specifying its parameter.
MethodCallExpression methodCall = Expression.Call(
    typeof(Console).GetMethod("WriteLine", new Type[] { typeof(int) }),

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
    new ParameterExpression[] { param }

// This code example produces the following output:
// 10

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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