12.4.1.2 C and C++ constants
GDB allows you to express the constants of C and C++ in the
following ways:
- Integer constants are a sequence of digits. Octal constants are
specified by a leading 0 (i.e. zero), and hexadecimal constants
by a leading 0x or 0X. Constants may also end with a letter
l, specifying that the constant should be treated as a
long
value.
- Floating point constants are a sequence of digits, followed by a decimal
point, followed by a sequence of digits, and optionally followed by an
exponent. An exponent is of the form:
e[[+]|-]nnn, where nnn is another
sequence of digits. The + is optional for positive exponents.
A floating-point constant may also end with a letter f or
F, specifying that the constant should be treated as being of
the
float
(as opposed to the default double
) type; or with
a letter l or L, which specifies a long double
constant.
- Enumerated constants consist of enumerated identifiers, or their
integral equivalents.
- Character constants are a single character surrounded by single quotes
(
'
), or a number—the ordinal value of the corresponding character
(usually its ascii value). Within quotes, the single character may
be represented by a letter or by escape sequences, which are of
the form \nnn, where nnn is the octal representation
of the character's ordinal value; or of the form \x, where
x is a predefined special character—for example,
\n for newline.
- String constants are a sequence of character constants surrounded by
double quotes (
"
). Any valid character constant (as described
above) may appear. Double quotes within the string must be preceded by
a backslash, so for instance "a\"b'c" is a string of five
characters.
- Pointer constants are an integral value. You can also write pointers
to constants using the C operator &.
- Array constants are comma-separated lists surrounded by braces {
and }; for example, {1,2,3} is a three-element array of
integers, {{1,2}, {3,4}, {5,6}} is a three-by-two array,
and {&"hi", &"there", &"fred"} is a three-element array of pointers.