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Attribute::IsDefined Method (ParameterInfo, Type)

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

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

static bool IsDefined(
	ParameterInfo^ element, 
	Type^ attributeType


Type: System.Reflection::ParameterInfo

An object derived from the ParameterInfo class that describes a parameter of a 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 nullptr.


attributeType is not derived from Attribute.

The ancestors of element are searched for custom attributes.

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

using namespace System;
using namespace System::Reflection;

namespace IsDef5CS
   public ref class TestClass

      // Assign a ParamArray attribute to the parameter using the keyword. 
      void Method1(... array<String^>^args ){}


   ref class DemoClass
      static void Main()

         // Get the class type to access its metadata.
         Type^ clsType = TestClass::typeid;

         // Get the MethodInfo object for Method1.
         MethodInfo^ mInfo = clsType->GetMethod( "Method1" );

         // Get the ParameterInfo array for the method parameters. 
         array<ParameterInfo^>^pInfo = mInfo->GetParameters();
         if ( pInfo != nullptr )

            // See if the ParamArray attribute is defined. 
            bool isDef = Attribute::IsDefined( pInfo[ 0 ], ParamArrayAttribute::typeid );

            // Display the result.
            Console::WriteLine( "The ParamArray attribute {0} defined for " 
            "parameter {1} of method {2}.", isDef ? (String^)"is" : "is not", pInfo[ 0 ]->Name, mInfo->Name );
                  Console::WriteLine( "The parameters information could " 
         "not be retrieved for method {0}.", mInfo->Name );



 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.

.NET Framework

Supported in: 4.6, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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