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4-4 Delphi Language Guide
Fundamental syntactic elements
Directives
Directives are words that are sensitive in specific locations within source code.
Directives have special meanings in the Delphi language, but, unlike reserved words,
appear only in contexts where user-defined identifiers cannot occur. Hence—
although it is inadvisable to do so—you can define an identifier that looks exactly
like a directive.
Numerals
Integer and real constants can be represented in decimal notation as sequences of
digits without commas or spaces, and prefixed with the + or – operator to indicate
sign. Values default to positive (so that, for example, 67258 is equivalent to +67258) and
must be within the range of the largest predefined real or integer type.
Numerals with decimal points or exponents denote reals, while other numerals
denote integers. When the character E or e occurs within a real, it means “times ten to
the power of”. For example, 7E–2 means 7
× 10
–2
, and 12.25e+6 and 12.25e6 both mean
12.25
× 10
6
.
The dollar-sign prefix indicates a hexadecimal numeral—for example, $8F.
Hexadecimal numbers without a preceding '-' unary operator are taken to be positive
values. During an assignment, if a hexadecimal value lies outside the range of the
receiving type an error is raised, except in the case of the Integer (32-bit Integer)
where a warning is raised. In this case, values exceeding the positive range for
Integer are taken to be negative numbers in a manner consistent with 2's complement
integer representation.
For more information about real and integer types, see Chapter 5, “Data types,
variables, and constants”. For information about the data types of numerals, see
“True constants” on page 5-43.
Table 4.3 Directives
absolute dynamic message private resident
abstract export name protected safecall
assembler external near public stdcall
automated far nodefault published stored
cdecl forward overload read varargs
contains implements override readonly virtual
default index package register write
deprecated library pascal reintroduce writeonly
dispid local platform requires