[olbeup]

Hola oscarac,

El tipo campo: Variant que has definido, puede tomar cualquier tipo y valor, lo que tienes que hacer es saber de que tipo es el valor que le has pasado a la función.

Código Delphi [-]
function CampoVacio(Campo: Variant): Boolean;
begin
  case VarType(Campo) of
    varDate: Result := (YearOf(Campo) <= 1900);
    varString: Result := (Campo = '');
    var...
  end;
end;

Un saludo.

p.d.: Aquí tienes el resto de tipos.

Returns the type code of a specified variant.

Unit

Variants

Category

Variant support routines

Delphi syntax:

function VarType(const V: Variant): TVarType;

C++ syntax:

extern PACKAGE TVarType __fastcall VarType(const Variant &V);

Description

VarType returns the type code of the given variant. The resulting value is either the type code for a custom Variant type, or it is constructed from the constants declared in the System unit.

The lower twelve bits of a variant type code (the bits defined by the varTypeMask bit mask) define the type of the variant. The varArray bit is set if the variant is an array of the given type. The varByRef bit is set if the variant is a reference to a value of the given type as opposed to an actual value.

The following table describes the meaning of each of the variant type codes defined in the System unit:

VarType Contents of variant

varEmpty The variant is Unassigned.
varNull The variant is Null.
varSmallint 16-bit signed integer (type Smallint in Delphi, short in C++ ).
varInteger 32-bit signed integer (type Integer in Delphi, int in C++).
varSingle Single-precision floating-point value (type Single in Delphi, float in C++).
varDouble Double-precision floating-point value (type double).
varCurrency Currency floating-point value (type Currency).
varDate Date and time value (type TDateTime).

varOleStr Reference to a dynamically allocated UNICODE string.
varDispatch Reference to an Automation object (an IDispatch interface pointer).
varError Operating system error code.
varBoolean 16-bit boolean (type WordBool).
varVariant A variant.
varUnknown Reference to an unknown object (an IInterface or IUnknown interface pointer).
varShortInt 8-bit signed integer (type ShortInt in Delphi or signed char in C++)
varByte A Byte
varWord unsigned 16-bit value (Word)

varLongWord unsigned 32-bit value (type LongWord in Delphi or unsigned long in C++)
varInt64 64-bit signed integer (Int64 in Delphi or __int64 in C++)
varStrArg COM-compatible string.
varString Reference to a dynamically allocated string (not COM compatible).
varAny A CORBA Any value.

The value returned by VarType corresponds to the VType field of a TVarData record.

The type of a variant can be changed using VarAsType.