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11/18/2011

Type.GetConstructors Method

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Returns all the public constructors defined for the current Type.

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Function GetConstructors As ConstructorInfo()

[ComVisibleAttribute(true)]
public ConstructorInfo[] GetConstructors()

Return Value

Type: array<System.Reflection.ConstructorInfo[]
An array of ConstructorInfo objects representing all the public instance constructors defined for the current Type, but not including the type initializer (static constructor). If no public instance constructors are defined for the current Type, or if the current Type represents a type parameter in the definition of a generic type or generic method, an empty array of type ConstructorInfo is returned.

Remarks

The GetConstructors method does not return constructors in a particular order, such as declaration order. Your code must not depend on the order in which constructors are returned, because that order varies.

The following table shows what members of a base class are returned by the Get methods when reflecting on a type.

Member Type	Static	Non-Static
Constructor	No	No
Field	No	Yes. A field is always hide-by-name-and-signature.
Event	Not applicable	The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.
Method	No	Yes. A method (both virtual and non-virtual) can be hide-by-name or hide-by-name-and-signature.
Nested Type	No	No
Property	Not applicable	The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.

Notes:

Hide-by-name-and-signature considers all of the parts of the signature, including custom modifiers, return types, parameter types, sentinels, and unmanaged calling conventions. This is a binary comparison.
For reflection, properties and events are hide-by-name-and-signature. If you have a property with both a get and a set accessor in the base class, but the derived class has only a get accessor, the derived class property hides the base class property, and you will not be able to access the setter on the base class.
Custom attributes are not part of the common type system.

This method overload calls the GetConstructors(BindingFlags) method overload, with BindingFlags.Public | BindingFlags.Instance (BindingFlags.PublicOrBindingFlags.Instance in Visual Basic). It will not find class initializers (.cctor). To find class initializers, use an overload that takes BindingFlags, and specify BindingFlags.Static | BindingFlags.NonPublic (BindingFlags.StaticOrBindingFlags.NonPublic in Visual Basic).

If the current Type represents a constructed generic type, this method returns the ConstructorInfo objects with the type parameters replaced by the appropriate type arguments. For example, if class C<T> has a constructor C(T t1) (Sub New(ByVal t1 As T) in Visual Basic), calling GetConstructors on C<int> returns a ConstructorInfo that represents C(int t1) in C# (Sub New(ByVal t1 As Integer) in Visual Basic).

If the current Type represents a generic type parameter, the GetConstructors method returns an empty array.

Examples

This example shows the result of calling the two GetConstructors overloads for a class that has a public instance constructor, a protected instance constructor, and a static constructor (Shared constructor in Visual Basic).

Because the GetConstructors() overload uses only BindingFlags.Public and BindingFlags.Instance, the static constructor and the protected instance constructor are not displayed.

To find all the constructors, use the GetConstructors(BindingFlags) overload with the combination (logical OR) of BindingFlags.Public, BindingFlags.Static, BindingFlags.NonPublic, and BindingFlags.Instance.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection

Public Class Example

   Protected Sub New()
   End Sub

   Shared Sub New()
   End Sub

   Public Sub New(ByVal i As Integer)
   End Sub

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      outputBlock.Text &= "Constructors found by GetConstructors():" & vbLf
      For Each ci As ConstructorInfo In GetType(Example).GetConstructors()
         outputBlock.Text &= ci.ToString() & vbLf
      Next

      outputBlock.Text &= vbLf & "Constructors found by GetConstructors(BindingFlags):" & vbLf
      For Each ci As ConstructorInfo In GetType(Example).GetConstructors( _
         BindingFlags.Public Or _
         BindingFlags.Static Or _
         BindingFlags.NonPublic Or _
         BindingFlags.Instance)

         outputBlock.Text &= ci.ToString() & vbLf
      Next
   End Sub
End Class

' This example produces the following output:
'
'Constructors found by GetConstructors():
'Void .ctor(Int32)
'
'Constructors found by GetConstructors(BindingFlags):
'Void .ctor()
'Void .cctor()
'Void .ctor(Int32)

using System.Reflection;

public class Example
{
   protected Example() {}

   static Example() {}

   public Example(int i) {}

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      outputBlock.Text += "Constructors found by GetConstructors():\n";
      foreach (ConstructorInfo ci in typeof(Example).GetConstructors())
      {
         outputBlock.Text += ci.ToString() + "\n";
      }

      outputBlock.Text += "\nConstructors found by GetConstructors(BindingFlags):\n";
      foreach (ConstructorInfo ci in typeof(Example).GetConstructors(
         BindingFlags.Public | BindingFlags.Static | BindingFlags.NonPublic |
         BindingFlags.Instance))
      {

         outputBlock.Text += ci.ToString() + "\n";
      }
   }
}

/* This example produces the following output:

Constructors found by GetConstructors():
Void .ctor(Int32)

Constructors found by GetConstructors(BindingFlags):
Void .ctor()
Void .cctor()
Void .ctor(Int32)
 */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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