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Type.GetConstructors Method (BindingFlags)

April 12, 2014

When overridden in a derived class, searches for the constructors defined for the current Type, using the specified BindingFlags.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
public abstract ConstructorInfo[] GetConstructors(
	BindingFlags bindingAttr
)

Parameters

bindingAttr
Type: System.Reflection.BindingFlags
A bitmask comprised of one or more BindingFlags that specify how the search is conducted.
-or-
Zero, to return null.

Return Value

Type: System.Reflection.ConstructorInfo []
An array of ConstructorInfo objects representing all constructors defined for the current Type that match the specified binding constraints, including the type initializer if it is defined. Returns an empty array of type ConstructorInfo if no constructors are defined for the current Type, if none of the defined constructors match the binding constraints, or if the current Type represents a type parameter in the definition of a generic type or generic method.

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.

bindingAttr can be used to specify whether to return only public constructors or both public and non-public constructors.

If an exact match does not exist, the binder will attempt to coerce the parameter types specified in the types array in order to select a match. If the binder is unable to select a match, then null is returned.

The following BindingFlags filter flags can be used to define which constructors to include in the search:

  • You must specify either BindingFlags.Instance or BindingFlags.Static in order to get a return.

  • Specify BindingFlags.Public to include public constructors in the search.

  • Specify BindingFlags.NonPublic to include non-public constructors (that is, private and protected constructors) in the search.

See System.Reflection.BindingFlags for more information.

To get the class initializer (.cctor) using this method overload, you must 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.

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.


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)
 */


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

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