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Type.GetConstructors Method (BindingFlags)

Updated: September 2009

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)

'Declaration
<ComVisibleAttribute(True)> _
Public MustOverride Function GetConstructors ( _
	bindingAttr As BindingFlags _
) As ConstructorInfo()
'Usage
Dim instance As Type 
Dim bindingAttr As BindingFlags 
Dim returnValue As ConstructorInfo()

returnValue = instance.GetConstructors(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 Nothing.

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.

Implements

_Type.GetConstructors(BindingFlags)

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 Nothing 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.Static Or BindingFlags.NonPublic in Visual Basic). You can also get the class initializer using the TypeInitializer property.

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 output of the GetConstructors overload from a class that has two instance constructors and one static constructor.

Imports System
Imports System.Reflection

Public Class t

    Public Sub New()
    End Sub 

    Shared Sub New()
    End Sub 

    Public Sub New(i As Integer)
    End Sub 

    Public Shared Sub Main()
        Dim p As ConstructorInfo() = GetType(t).GetConstructors()
        Console.WriteLine(p.Length)

        Dim i As Integer 
        For i = 0 To p.Length - 1
            Console.WriteLine(p(i).IsStatic)
        Next i
    End Sub 
End Class

The output of this code is:

2

False

False

Because the GetConstructors overload uses only Public and Instance, the static constructor is neither counted by the for expression nor evaluated by IsStatic.

To find static constructors, use the GetConstructors overload, and pass it the combination (logical OR) of BindingFlags.Public, BindingFlags.Static, BindingFlags.NonPublic, BindingFlags.Instance, as shown in the following code example:

Imports System
Imports System.Reflection

Public Class t

    Public Sub New()
    End Sub 

    Shared Sub New()
    End Sub 

    Public Sub New(i As Integer)
    End Sub 

    Public Shared Sub Main()
        Dim p As ConstructorInfo() = GetType(T).GetConstructors( _
           BindingFlags.Public Or _
           BindingFlags.Static Or _
           BindingFlags.NonPublic Or _
           BindingFlags.Instance)
        Console.WriteLine(p.Length)

        Dim i As Integer 
        For i = 0 To p.Length - 1
            Console.WriteLine(p(i).IsStatic)
        Next i
    End Sub 
End Class

Now the output is:

3

False

True

False

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

Date

History

Reason

September 2009

Removed an erroneous statement that Nothing is returned for non-public members outside the assembly, if caller lacks ReflectionPermission.

Content bug fix.

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