UnmanagedType Enumeration
Identifies how to marshal parameters or fields to unmanaged code.
Assembly: mscorlib (in mscorlib.dll)
| Member name | Description | |
|---|---|---|
![]() ![]() | Bool | A 4-byte Boolean value (true != 0, false = 0). This is the Win32 BOOL type. |
![]() ![]() | I1 | 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 | A 1-byte unsigned integer. |
![]() ![]() | I2 | A 2-byte signed integer. |
![]() ![]() | U2 | A 2-byte unsigned integer. |
![]() ![]() | I4 | A 4-byte signed integer. |
![]() ![]() | U4 | A 4-byte unsigned integer. |
![]() ![]() | I8 | An 8-byte signed integer. |
![]() ![]() | U8 | An 8-byte unsigned integer. |
![]() ![]() | R4 | A 4-byte floating point number. |
![]() ![]() | R8 | An 8-byte floating point number. |
![]() ![]() | Currency | Used on a System.Decimal to marshal the decimal value as a COM currency type instead of as a Decimal. |
![]() | BStr | 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 | A single byte, null-terminated ANSI character string. You can use this member on the System.String or System.Text.StringBuilder data types |
![]() ![]() | LPWStr | A 2-byte, null-terminated Unicode character string. Note that you cannot use the LPWStr value with an unmanaged string unless the string was created using the unmanaged CoTaskMemAlloc function. |
![]() ![]() | LPTStr | A platform-dependent character string: ANSI on Windows 98 and Unicode on Windows NT and Windows XP. This value is only supported for platform invoke, and not COM interop, because exporting a string of type LPTStr is not supported. |
![]() ![]() | ByValTStr | Used for in-line, fixed-length character arrays that appear within a structure. The character type used with ByValTStr is determined by the System.Runtime.InteropServices.CharSet argument of the System.Runtime.InteropServices.StructLayoutAttribute applied to the containing structure. Always use the MarshalAsAttribute.SizeConst field to indicate the size of the array. .NET Framework ByValTStr types behave like C-style, fixed-size strings inside a structure (for example, char s[5]). The behavior in managed code differs from the Microsoft Visual Basic 6.0 behavior, which is not null terminated (for example, MyString As String * 5). |
![]() | IUnknown | A COM IUnknown pointer. You can use this member on the Object data type. |
![]() | IDispatch | A COM IDispatch pointer (Object in Microsoft Visual Basic 6.0). |
![]() ![]() | Struct | A VARIANT, which is used to marshal managed formatted classes and value types. |
![]() | Interface | 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 UnmanagedType.IUnknown behavior when you apply it to the Object data type. |
![]() | SafeArray | A SafeArray is a self-describing array that carries the type, rank, and bounds of the associated array data. You can use this member with the MarshalAsAttribute.SafeArraySubType field to override the default element type. |
![]() ![]() | ByValArray | When MarshalAsAttribute.Value is set to ByValArray, the SizeConst 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 only use this UnmanagedType on an array that appear as fields in a structure. |
![]() ![]() | SysInt | A platform-dependent, signed integer. 4-bytes on 32 bit Windows, 8-bytes on 64 bit Windows. |
![]() ![]() | SysUInt | A platform-dependent, unsigned integer. 4-bytes on 32 bit Windows, 8-bytes on 64 bit Windows. |
![]() | VBByRefStr | Allows Visual Basic 2005 to change a string in unmanaged code, and have the results reflected in managed code. This value is only supported for platform invoke. |
![]() | AnsiBStr | An ANSI character string that is a length prefixed, single byte. You can use this member on the String data type. |
![]() | TBStr | A length-prefixed, platform-dependent char string. ANSI on Windows 98, Unicode on Windows NT. You rarely use this BSTR-like member. |
![]() | VariantBool | A 2-byte, OLE-defined VARIANT_BOOL type (true = -1, false = 0). |
![]() | FunctionPtr | An integer that can be used as a C-style function pointer. You can use this member on a Delegate data type or a type that inherits from a Delegate. |
![]() ![]() | AsAny | A dynamic type that determines the type of an object at run time and marshals the object as that type. Valid for platform invoke methods only. |
![]() ![]() | LPArray | A pointer to the first element of a C-style array. When marshaling from managed to unmanaged, the length of the array is determined by the length of the managed array. When marshaling from unmanaged to managed, the length of the array is determined from the MarshalAsAttribute.SizeConst and the MarshalAsAttribute.SizeParamIndex fields, optionally followed by the unmanaged type of the elements within the array when it is necessary to differentiate among string types. |
![]() ![]() | LPStruct | A pointer to a C-style structure that you use to marshal managed formatted classes. Valid for platform invoke methods only. |
![]() | CustomMarshaler | Specifies the custom marshaler class when used with MarshalAsAttribute.MarshalType or MarshalAsAttribute.MarshalTypeRef. The MarshalAsAttribute.MarshalCookie field can be used to pass additional information to the custom marshaler. You can use this member on any reference type. |
![]() ![]() | Error | This native type associated with an I4 or a U4 causes the parameter to be exported as a HRESULT in the exported type library. |
Use the UnmanagedType enumeration with the System.Runtime.InteropServices.MarshalAsAttribute 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.
Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note: The .NET Compact Framework does not support all of the UnmanagedType enumeration values. For more information, see Using the MarshalAsAttribute Attribute
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 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 serveral UnmanagedType members, which represent the types used by the original COM interface.
Imports System 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)> 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
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.
