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Attribute.IsDefined Method (MemberInfo, Type)

Determines whether any custom attributes are applied to a member of a type. Parameters specify the member, and the type of the custom attribute to search for.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static bool IsDefined(
	MemberInfo element,
	Type attributeType


Type: System.Reflection.MemberInfo

An object derived from the MemberInfo class that describes a constructor, event, field, method, type, or property member of a class.

Type: System.Type

The type, or a base type, of the custom attribute to search for.

Return Value

Type: System.Boolean
true if a custom attribute of type attributeType is applied to element; otherwise, false.


element or attributeType is null.


attributeType is not derived from Attribute.


element is not a constructor, method, property, event, type, or field.

The ancestors of element are searched for custom attributes.


Starting with the .NET Framework version 2.0, this method returns true if a type, method, or constructor has security attributes stored in the new metadata format. Assemblies compiled with version 2.0 or later use the new format. Dynamic assemblies and assemblies compiled with earlier versions of the .NET Framework use the old XML format. See Emitting Declarative Security Attributes.

The following code example illustrates the use of IsDefined, taking a MemberInfo as a parameter.

using System;
using System.Reflection;

namespace IsDef4CS 
    public class TestClass 
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        public void Method2()

    public class DemoClass 
        static void Main(string[] args) 
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method. 
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message. 
            if (isDef) 
                ObsoleteAttribute obsAttr = 
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                    Console.WriteLine("The message could not be retrieved.");

 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0