Debugging with GDB
12.4.2.3 Constants
GDB allows you to express the constants of Modula2 in the following
ways:

Integer constants are simply a sequence of digits. When used in an
expression, a constant is interpreted to be typecompatible with the
rest of the expression. Hexadecimal integers are specified by a
trailing `H', and octal integers by a trailing `B'.

Floating point constants appear as a sequence of digits, followed by a
decimal point and another sequence of digits. An optional exponent can
then be specified, in the form `E[+]nnn', where
`[+]nnn' is the desired exponent. All of the
digits of the floating point constant must be valid decimal (base 10)
digits.

Character constants consist of a single character enclosed by a pair of
like quotes, either single (
'
) or double ("
). They may
also be expressed by their ordinal value (their ASCII value, usually)
followed by a `C'.

String constants consist of a sequence of characters enclosed by a
pair of like quotes, either single (
'
) or double ("
).
Escape sequences in the style of C are also allowed. See section C and C++ constants, for a brief explanation of escape
sequences.

Enumerated constants consist of an enumerated identifier.

Boolean constants consist of the identifiers
TRUE
and
FALSE
.

Pointer constants consist of integral values only.

Set constants are not yet supported.