Valid Types

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In the Type Library editor, you use different type identifiers, depending on whether you are working in IDL or Delphi. Specify the language you want to use in the Environment options dialog.

The following types are valid in a type library for COM development. The Automation-compatible column specifies whether the type can be used by an interface that has its Automation or Dispinterface flag checked. These are the types that COM can marshal via the type library automatically:

Delphi type IDL type Variant type Automation compatible Description

Smallint

short

VT_I2

Yes

2-byte signed integer

Integer

long

VT_I4

Yes

4-byte signed integer

Single

single

VT_R4

Yes

4-byte real

Double

double

VT_R8

Yes

8-byte real

Currency

CURRENCY

VT_CY

Yes

currency

TDateTime

DATE

VT_DATE

Yes

date

WideString

BSTR

VT_BSTR

Yes

binary string

IDispatch

IDispatch

VT_DISPATCH

Yes

pointer to IDispatch interface

SCODE

SCODE

VT_ERROR

Yes

Ole Error Code

WordBool

VARIANT_BOOL

VT_BOOL

Yes

True = -1, False = 0

OleVariant

VARIANT

VT_VARIANT

Yes

Ole Variant

IUnknown

IUnknown

VT_UNKNOWN

Yes

pointer to IUnknown interface

Shortint

byte

VT_I1

No

1 byte signed integer

Byte

unsigned char

VT_UI1

Yes

1-byte unsigned integer

Word

unsigned short

VT_UI2

Yes*

2-byte unsigned integer

LongWord

unsigned long

VT_UI4

Yes*

4-byte unsigned integer

Int64

__int64

VT_I8

No

8-byte signed integer

Largeuint

uint64

VT_UI8

No

8-byte unsigned integer

SYSINT

int

VT_INT

Yes*

system dependent integer (Win32=Integer)

SYSUINT

unsigned int

VT_UINT

Yes*

system-dependent unsigned integer

HResult

HRESULT

VT_HRESULT

No

32-bit error code

Pointer

VT_PTR -> VT_VOID

No

untyped pointer

SafeArray

SAFEARRAY

VT_SAFEARRAY

No

OLE Safe Array

PAnsiChar

LPSTR

VT_LPSTR

No

pointer to Char

PChar

LPWSTR

VT_LPWSTR

No

pointer to WideChar

PWideChar

LPWSTR

VT_LPWSTR

No

pointer to WideChar


Note: Word, LongWord, SYSINT, and SYSUINT may be Automation-compatible with some applications.

See SafeArrays for more information about the SAFEARRAY Variant type.

Note: The Byte (VT_UI1) is Automation-compatible, but is not allowed in a Variant or OleVariant because many Automation servers do not handle this value correctly.

Besides these IDL types, any interfaces and types defined in the library or defined in referenced libraries can be used in a type library definition.

The Type Library editor stores type information in the generated type library (.TLB) file in binary form.

If a parameter type is specified as a Pointer type, the Type Library editor usually translates that type into a variable parameter. When the type library is saved, the variable parameter's associated ElemDesc's IDL flags are marked IDL_FIN or IDL_FOUT.

Often, ElemDesc IDL flags are not marked by IDL_FIN or IDL_FOUT when the type is preceded with a Pointer. Or, in the case of dispinterfaces, IDL flags are not typically used. In these cases, you may see a comment next to the variable identifier such as {IDL_None} or {IDL_In}. These comments are used when saving a type library to correctly mark the IDL flags.