ParameterInfo.IsDefined Method (Type, Boolean)


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Determines whether the custom attribute of the specified type or its derived types is applied to this parameter.

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

public virtual bool IsDefined(
	Type attributeType,
	bool inherit


Type: System.Type

The Type object to search for.

Type: System.Boolean

This argument is ignored for objects of this type. See Remarks.

Return Value

Type: System.Boolean

true if one or more instances of attributeType or its derived types are applied to this parameter; otherwise, false.

Exception Condition

attributeType is null.


attributeType is not a Type object supplied by the common language runtime.

This method ignores the inherit parameter. To search the inheritance chain for attributes on parameters, use the appropriate overloads of the Attribute.IsDefined method.

The following example defines two custom attributes, MyAttribute and MyDerivedAttribute. MyDerivedAttribute is derived from MyAttribute. The example then applies these attributes to the parameters of a method of an example class.

When the example is run, it uses the IsDefined method to test all parameters of all methods in the example class. It then displays the parameters that have MyAttribute or MyDerivedAttribute.

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
public class MyAttribute : Attribute
    private string myName;
    public MyAttribute(string name)
        myName = name;
    public string Name 
            return myName;

// Derive another custom attribute from MyAttribute
public class MyDerivedAttribute : MyAttribute
    public MyDerivedAttribute(string name) : base(name) {}

// Define a class with a method that has three parameters. Apply
// MyAttribute to one parameter, MyDerivedAttribute to another, and
// no attributes to the third. 
public class MyClass1
    public void MyMethod(
        [MyAttribute("This is an example parameter attribute")]
        int i,
        [MyDerivedAttribute("This is another parameter attribute")]
        int j,
        int k )

public class MemberInfo_GetCustomAttributes 
    public static void Main()
        // Get the type of the class 'MyClass1'.
        Type myType = typeof(MyClass1);
        // Get the members associated with the class 'MyClass1'.
        MethodInfo[] myMethods = myType.GetMethods();

        // For each method of the class 'MyClass1', display all the parameters
        // to which MyAttribute or its derived types have been applied.
        foreach (MethodInfo mi in myMethods)
            // Get the parameters for the method.
            ParameterInfo[] myParameters = mi.GetParameters();
            if (myParameters.Length > 0)
                Console.WriteLine("\nThe following parameters of {0} have MyAttribute or a derived type: ", mi);
                foreach (ParameterInfo pi in myParameters)
                    if (pi.IsDefined(typeof(MyAttribute), false))
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2}", 
                            pi.Position, pi.Name, pi.ParameterType);

/* This code example produces the following output:

The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
Parameter 0, name = i, type = System.Int32
Parameter 1, name = j, type = System.Int32

The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:

.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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