Type.GetConstructors Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Gets the constructors of the current Type.

Overloads

GetConstructors()	Returns all the public constructors defined for the current Type.
GetConstructors(BindingFlags)	When overridden in a derived class, searches for the constructors defined for the current Type, using the specified BindingFlags.

Examples

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

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 );

   }
}

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);
        }
    }
}

type t() =
    static do ()
    new(i: int) = t ()

let p = typeof<t>.GetConstructors()
printfn $"{p.Length}"

for c in p do
    printfn $"{c.IsStatic}"

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:

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 );
   }
}

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);
        }
    }
}

open System.Reflection

type t() =
    static do ()
    new (i: int) = t ()

let p = typeof<t>.GetConstructors(BindingFlags.Public ||| BindingFlags.Static ||| BindingFlags.NonPublic ||| BindingFlags.Instance)
printfn $"{p.Length}"

for c in p do
    printfn $"{c.IsStatic}"

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

GetConstructors()

Source:

Type.cs

Returns all the public constructors defined for the current Type.

public:
 cli::array <System::Reflection::ConstructorInfo ^> ^ GetConstructors();

public System.Reflection.ConstructorInfo[] GetConstructors ();

member this.GetConstructors : unit -> System.Reflection.ConstructorInfo[]

Public Function GetConstructors () As ConstructorInfo()

Returns

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

In .NET 6 and earlier versions, 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. However, starting with .NET 7, the ordering is deterministic based upon the metadata ordering in the assembly.

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.

1. 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.

2. 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.

3. 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 (static constructor). To find class initializers, use an overload that takes BindingFlags, and specify BindingFlags.Static | BindingFlags.NonPublic (BindingFlags.StaticOrBindingFlags.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.

See also

• ConstructorInfo
• GetConstructor(BindingFlags, Binder, CallingConventions, Type[], ParameterModifier[])

GetConstructors(BindingFlags)

Source:

Type.cs

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

public:
 abstract cli::array <System::Reflection::ConstructorInfo ^> ^ GetConstructors(System::Reflection::BindingFlags bindingAttr);

public abstract System.Reflection.ConstructorInfo[] GetConstructors (System.Reflection.BindingFlags bindingAttr);

abstract member GetConstructors : System.Reflection.BindingFlags -> System.Reflection.ConstructorInfo[]

Public MustOverride Function GetConstructors (bindingAttr As BindingFlags) As ConstructorInfo()

Parameters

bindingAttr

BindingFlags

A bitwise combination of the enumeration values that specify how the search is conducted.

-or-

Default to return an empty array.

Returns

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's 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.

Remarks

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

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

• Specify BindingFlags.Static along with BindingFlags.NonPublic to retrieve the class initializer (static constructor). You can also get the class initializer using the TypeInitializer property.

• Specify BindingFlags.Instance along with one or both of BindingFlags.Public and BindingFlags.NonPublic to retrieve instance constructors.

See System.Reflection.BindingFlags for more information.

In .NET 6 and earlier versions, 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. However, starting with .NET 7, the ordering is deterministic based upon the metadata ordering in the assembly.

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.

See also

• ConstructorInfo
• BindingFlags
• DefaultBinder
• GetConstructor(BindingFlags, Binder, CallingConventions, Type[], ParameterModifier[])