Type.GetConstructors Method (System)

GetConstructors Method

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

Type..::.GetConstructors Method

Returns all the public constructors defined for the current Type.

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

Syntax

Visual Basic (Declaration)

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

Visual Basic (Usage)

Dim instance As Type
Dim returnValue As ConstructorInfo()

returnValue = instance.GetConstructors()

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

Visual C++

[ComVisibleAttribute(true)]
public:
virtual array<ConstructorInfo^>^ GetConstructors() sealed

JScript

public final function GetConstructors() : ConstructorInfo[]

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.

Implements

_Type..::.GetConstructors()()()

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.

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..::.Public Or BindingFlags..::.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..::.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.

Examples

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

Visual Basic

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

using System;
using System.Reflection;

public class t {
    public t() {}
    static t() {}
    public t(int i) {}

    public static void Main() {
        ConstructorInfo[] p = typeof(t).GetConstructors();
        Console.WriteLine(p.Length);

        for (int i=0;i<p.Length;i++) {
            Console.WriteLine(p[i].IsStatic);
        }
    }
}

Visual C++

using namespace System;
using namespace System::Reflection;
public ref class t
{
public:
   t(){}

   static t(){}

   t( int /*i*/ ){}

};

int main()
{
   array<ConstructorInfo^>^p = t::typeid->GetConstructors();
   Console::WriteLine( p->Length );
   for ( int i = 0; i < p->Length; i++ )
   {
      Console::WriteLine( p[ i ]->IsStatic );

   }
}

JScript

import System;
import System.Reflection;

public class t {
    public function t() {}
    static t {}
    public function t(i : int) {}

    public static function Main(): void  {
        var p : ConstructorInfo[] = t.GetConstructors();
        Console.WriteLine(p.Length);

        for (var i : int =0;i<p.Length;i++) {
            Console.WriteLine(p[i].IsStatic);
        }
    }
}
t.Main();

The output of this code is:

False

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

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

Visual Basic

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

using System;
using System.Reflection;

public class t {
    public t() {}
    static t() {}
    public t(int i) {}

    public static void Main() {
        ConstructorInfo[] p = typeof(t).GetConstructors(
           BindingFlags.Public | BindingFlags.Static |
           BindingFlags.NonPublic | BindingFlags.Instance);
        Console.WriteLine(p.Length);

        for (int i=0;i<p.Length;i++) {
            Console.WriteLine(p[i].IsStatic);
        }
    }
}

Visual C++

using namespace System;
using namespace System::Reflection;
public ref class t
{
public:
   t(){}

   t( int /*i*/ ){}

   static t(){}

};

int main()
{
   array<ConstructorInfo^>^p = t::typeid->GetConstructors( static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Static | BindingFlags::NonPublic | BindingFlags::Instance) );
   Console::WriteLine( p->Length );
   for ( int i = 0; i < p->Length; i++ )
   {
      Console::WriteLine( p[ i ]->IsStatic );
   }
}

JScript

import System;
import System.Reflection;

public class t {
    public function t() {}
    static t {}
    public function t(i : int) {}

    public static function Main() : void  {
        var p : ConstructorInfo[] = t.GetConstructors(
           BindingFlags.Public | BindingFlags.Static |
           BindingFlags.NonPublic | BindingFlags.Instance);
        Console.WriteLine(p.Length);

        for (var i:int=0;i<p.Length;i++) {
            Console.WriteLine(p[i].IsStatic);
        }
    }
}
t.Main();

Now the output is:

False

True

False

Platforms

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.

Version Information

.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

Reference

Type Class

Type Members

GetConstructors Overload

System Namespace

ConstructorInfo

GetConstructor