UnmanagedType Enum

Definition

Namespace:

System.Runtime.InteropServices

Assembly:

System.Runtime.dll

Identifies how to marshal parameters or fields to unmanaged code.

public enum class UnmanagedType

public enum UnmanagedType

type UnmanagedType = 

Public Enum UnmanagedType

Inheritance

Object

ValueType

Enum

UnmanagedType

Fields

Name	Value	Description
Bool	2	A 4-byte Boolean value (true != 0, false = 0). This is the Win32 BOOL type.
I1	3	A 1-byte signed integer. You can use this member to transform a Boolean value into a 1-byte, C-style bool (true = 1, false = 0).
U1	4	A 1-byte unsigned integer.
I2	5	A 2-byte signed integer.
U2	6	A 2-byte unsigned integer.
I4	7	A 4-byte signed integer.
U4	8	A 4-byte unsigned integer.
I8	9	An 8-byte signed integer.
U8	10	An 8-byte unsigned integer.
R4	11	A 4-byte floating-point number.
R8	12	An 8-byte floating-point number.
Currency	15	A currency type. Used on a Decimal to marshal the decimal value as a COM currency type instead of as a Decimal.
BStr	19	A Unicode character string that is a length-prefixed double byte. You can use this member, which is the default string in COM, on the String data type.
LPStr	20	A single byte, null-terminated ANSI character string. You can use this member on the String and StringBuilder data types.
LPWStr	21	A 2-byte, null-terminated Unicode character string. You cannot use the LPWStr value with an unmanaged string unless the string was created by using the unmanaged CoTaskMemAlloc function.
LPTStr	22	A Unicode character string. This value is supported only for platform invoke and not for COM interop, because exporting a string of type LPTStr is not supported.
ByValTStr	23	Used for in-line, fixed-length character arrays that appear within a structure. ByValTStr types behave like C-style, fixed-size strings inside a structure (for example, char s[5]). The character type used with ByValTStr is determined by the CharSet argument of the StructLayoutAttribute attribute applied to the containing structure. Always use the SizeConst field to indicate the size of the array.
IUnknown	25	A COM IUnknown pointer. You can use this member on the Object data type.
IDispatch	26	A COM IDispatch pointer (Object in Microsoft Visual Basic 6.0).
Struct	27	A VARIANT, which is used to marshal managed formatted classes and value types.
Interface	28	A COM interface pointer. The Guid of the interface is obtained from the class metadata. Use this member to specify the exact interface type or the default interface type if you apply it to a class. This member produces the same behavior as IUnknown when you apply it to the Object data type.
SafeArray	29	A SafeArray, which is a self-describing array that carries the type, rank, and bounds of the associated array data. You can use this member with the SafeArraySubType field to override the default element type.
ByValArray	30	When the Value property is set to ByValArray, the SizeConst field must be set to indicate the number of elements in the array. The ArraySubType field can optionally contain the UnmanagedType of the array elements when it is necessary to differentiate among string types. You can use this UnmanagedType only on an array that whose elements appear as fields in a structure.
SysInt	31	A platform-dependent, signed integer: 4 bytes on 32-bit Windows, 8 bytes on 64-bit Windows.
SysUInt	32	A platform-dependent, unsigned integer: 4 bytes on 32-bit Windows, 8 bytes on 64-bit Windows.
VBByRefStr	34	A value that enables Visual Basic to change a string in unmanaged code and have the results reflected in managed code. This value is only supported for platform invoke.
AnsiBStr	35	An ANSI character string that is a length-prefixed single byte. You can use this member on the String data type.
TBStr	36	A length-prefixed, Unicode char string. You rarely use this BSTR-like member.
VariantBool	37	A 2-byte, OLE-defined VARIANT_BOOL type (true = -1, false = 0).
FunctionPtr	38	An integer that can be used as a C-style function pointer. You can use this member on a Delegate data type or on a type that inherits from a Delegate.
AsAny	40	A dynamic type that determines the type of an object at run time and marshals the object as that type. This member is valid for platform invoke methods only.
LPArray	42	A pointer to the first element of a C-style array. When marshaling from managed to unmanaged code, the length of the array is determined by the length of the managed array. When marshaling from unmanaged to managed code, the length of the array is determined from the SizeConst and SizeParamIndex fields, optionally followed by the unmanaged type of the elements within the array when it is necessary to differentiate among string types.
LPStruct	43	A pointer to a C-style structure that you use to marshal managed formatted classes. This member is valid for platform invoke methods only.
CustomMarshaler	44	Specifies the custom marshaler class when used with the MarshalType or MarshalTypeRef field. The MarshalCookie field can be used to pass additional information to the custom marshaler. You can use this member on any reference type. This member is valid for parameters and return values only. It cannot be used on fields.
Error	45	A native type that is associated with an I4 or an U4 and that causes the parameter to be exported as an HRESULT in the exported type library.
IInspectable	46	A Windows Runtime interface pointer. You can use this member on the Object data type. Built-in support for WinRT was removed in .NET 5.
HString	47	A Windows Runtime string. You can use this member on the String data type. Built-in support for WinRT was removed in .NET 5. See Formerly built-in supported types for workaround.
LPUTF8Str	48	A pointer to a UTF-8 encoded string.

Examples

The following code fragment demonstrates how to declare, in managed source code, an unmanaged interface implemented by a COM component. The System.Runtime.InteropServices.ComImportAttribute attribute prevents the IMyStorage interface from being exported back for use by COM. (COM clients should use the existing COM component directly.) In this example, MarshalAsAttribute specifies several UnmanagedType members, which represent the types used by the original COM interface.

using namespace System;
using namespace System::Runtime::InteropServices;

// If you do not have a type library for an interface
// you can redeclare it using ComImportAttribute.
// This is how the interface would look in an idl file.
//[
//object,
//uuid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26"),
//dual, helpstring("IMyStorage Interface"),
//pointer_default(unique)
//]
//interface IMyStorage : IDispatch
//{
// [id(1)]
// HRESULT GetItem([in] BSTR bstrName, [out, retval] IDispatch ** ppItem);
// [id(2)]
// HRESULT GetItems([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT)* pItems);
// [id(3)]
// HRESULT GetItemDescriptions([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT) ** ppItems);
// [id(4), propget]
// HRESULT get_IsEmpty([out, retval] BOOL * pfEmpty);
//};
// This is the managed declaration.

[ComImport]
[Guid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26")]
interface class IMyStorage
{
   [DispId(1)]
   Object^ GetItem( [In,MarshalAs(UnmanagedType::BStr)]String^ bstrName );

   //[return : MarshalAs(UnmanagedType::Interface)]

   [DispId(2)]
   void GetItems( [In,MarshalAs(UnmanagedType::BStr)]String^ bstrLocation, [Out,MarshalAs(UnmanagedType::SafeArray,
   SafeArraySubType=VarEnum::VT_VARIANT)]array<Object^>^Items );

   [DispId(3)]
   void GetItemDescriptions( [In]String^ bstrLocation, [In,Out,MarshalAs(UnmanagedType::SafeArray)]array<Object^>^varDescriptions );

   property bool IsEmpty 
   {
      [DispId(4)]
      [returnvalue:MarshalAs(UnmanagedType::VariantBool)]
      bool get();
   }
};

using System;
using System.Runtime.InteropServices;

namespace MyModule
{
    // If you do not have a type library for an interface
    // you can redeclare it using ComImportAttribute.

    // This is how the interface would look in an idl file.

    //[
    //object,
    //uuid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26"),
    //dual,	helpstring("IMyStorage Interface"),
    //pointer_default(unique)
    //]
    //interface IMyStorage : IDispatch
    //{
    //	[id(1)]
    //	HRESULT GetItem([in] BSTR bstrName, [out, retval] IDispatch ** ppItem);
    //	[id(2)]
    //	HRESULT GetItems([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT)* pItems);
    //	[id(3)]
    //	HRESULT GetItemDescriptions([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT) ** ppItems);
    //	[id(4), propget]
    //	HRESULT get_IsEmpty([out, retval] BOOL * pfEmpty);
    //};

    // This is the managed declaration.

    [ComImport]
    [Guid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26")]
    public interface IMyStorage
    {
        [DispId(1)]
        [return: MarshalAs(UnmanagedType.Interface)]
        object GetItem([In, MarshalAs(UnmanagedType.BStr)] String bstrName);

        [DispId(2)]
        void GetItems([In, MarshalAs(UnmanagedType.BStr)] String bstrLocation,
            [Out, MarshalAs( UnmanagedType.SafeArray,
                      SafeArraySubType = VarEnum.VT_VARIANT )] out Object[] Items);

        [DispId(3)]
        void GetItemDescriptions([In] String bstrLocation,
            [In, Out, MarshalAs(UnmanagedType.SafeArray)] ref Object[] varDescriptions);

        bool IsEmpty
        {
            [DispId(4)]
            [return: MarshalAs(UnmanagedType.VariantBool)]
            get;
        }
    }
}

Imports System.Runtime.InteropServices

Module MyModule
    ' If you do not have a type library for an interface
    ' you can redeclare it using ComImportAttribute.

    ' This is how the interface would look in an idl file.

    '[
    'object,
    'uuid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26"),
    'dual,	helpstring("IMyStorage Interface"),
    'pointer_default(unique)
    ']
    'interface IMyStorage : IDispatch
    '{
    '	[id(1)]
    '	HRESULT GetItem([in] BSTR bstrName, [out, retval] IDispatch ** ppItem);
    '	[id(2)]
    '	HRESULT GetItems([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT)* pItems);
    '	[id(3)]
    '	HRESULT GetItemDescriptions([in] BSTR bstrLocation, [out] SAFEARRAY(VARIANT) ** ppItems);
    '	[id(4), propget]
    '	HRESULT get_IsEmpty([out, retval] BOOL * pfEmpty);
    '};

    ' This is the managed declaration.

    <ComImport(), Guid("73EB4AF8-BE9C-4b49-B3A4-24F4FF657B26")> _
    Public Interface IMyStorage
        <DispId(1)> _
        Function GetItem(<InAttribute(), MarshalAs(UnmanagedType.BStr)> ByVal bstrName As String) _
           As <MarshalAs(UnmanagedType.Interface)> Object

        <DispId(2)> _
        Function GetItems(<InAttribute(), MarshalAs(UnmanagedType.BStr)> ByVal bstrLocation As String, _
           <OutAttribute(), MarshalAs(UnmanagedType.SafeArray, SafeArraySubType := VarEnum.VT_VARIANT)> _
                                      ByVal Items() As Object)

        <DispId(3)> _
        Function GetItemDescriptions(<InAttribute()> ByVal bstrLocation As String, _
           <InAttribute(), OutAttribute(), _
                      MarshalAs(UnmanagedType.SafeArray)> ByRef varDescriptions() As Object)

        <DispId(4)> _
        ReadOnly Property IsEmpty(<MarshalAs(UnmanagedType.VariantBool)> ByVal bEmpty As Boolean)

    End Interface
End Module

Remarks

Use the UnmanagedType enumeration with the System.Runtime.InteropServices.MarshalAsAttribute attribute to specify how types are marshaled during interoperation with unmanaged code. You can use this enumeration to marshal code using simple value types (I1, I2, I4, I8, R4, R8, U2, U4, and U8), unmanaged types that are unavailable in the .NET Framework, and various miscellaneous types.

For more information, see Interoperating with Unmanaged Code.

See also

• MarshalAsAttribute
• ComImportAttribute