Delphi in a Nutshell

Chapter 6. System Constants

This chapter is separate from Chapter 5, to make it easier to find the information you need. Instead of cluttering Chapter 5 with all the individual identifiers, this chapter organizes the system constants logically. All the constant literals described in this chapter are defined in the System unit, so they are available at all times.

Variant Type Codes

The VarType function returns the type code of a Variant. The type code is a small integer that contains a type identifier with the optional modifiers varArray and varByRef. Any type except varEmpty and varNull can have the varArray modifier. Delphi automatically takes care of the varByRef modifier. For more information, see the discussion of the Variant type in Chapter 5. Table 6-1 lists the type identifiers, and Table 6-2 lists the optional modifiers.

Table 6-1. Variant Type Identifiers

Literal	Value	Description
varEmpty	$0000	Variant not assigned
varNull	$0001	Null value
varSmallint	$0002	16-bit, signed integer
varInteger	$0003	32-bit, signed integer
varSingle	$0004	32-bit floating-point number
varDouble	$0005	64-bit floating-point number
varCurrency	$0006	64-bit fixed point number with four decimal places
varDate	$0007	64-bit floating-point date and time
varOleStr	$0008	#0-terminated wide string
varDispatch	$0009	IDispatch interface
varError	$000A	32-bit error code
varBoolean	$000B	Logical True or False
varVariant	$000C	Pointer to another Variant
varUnknown ...