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Operators must be defined on values of specific types. For instance,
+
is defined on numbers, but not on structures. Operators are
often defined on groups of types.
For the purposes of C and C++, the following definitions hold:
int
with any of its storageclass
specifiers; char
; enum
; and, for C++, bool
.
float
, double
, and
long double
(if supported by the target platform).
(type *)
.
The following operators are supported. They are listed here in order of increasing precedence:
,
The comma or sequencing operator. Expressions in a commaseparated list are evaluated from left to right, with the result of the entire expression being the last expression evaluated.
=
Assignment. The value of an assignment expression is the value assigned. Defined on scalar types.
op=
Used in an expression of the form a op= b
,
and translated to a = a op b
.
op=
and =
have the same precedence. The operator
op is any one of the operators 
, ^
, &
,
<<
, >>
, +
, 
, *
, /
, %
.
?:
The ternary operator. a ? b : c
can be thought
of as: if a then b else c. The argument a
should be of an integral type.

Logical OR. Defined on integral types.
&&
Logical AND. Defined on integral types.

Bitwise OR. Defined on integral types.
^
Bitwise exclusiveOR. Defined on integral types.
&
Bitwise AND. Defined on integral types.
==, !=
Equality and inequality. Defined on scalar types. The value of these expressions is 0 for false and nonzero for true.
<, >, <=, >=
Less than, greater than, less than or equal, greater than or equal. Defined on scalar types. The value of these expressions is 0 for false and nonzero for true.
<<, >>
left shift, and right shift. Defined on integral types.
@
The GDB “artificial array” operator (see Expressions).
+, 
Addition and subtraction. Defined on integral types, floatingpoint types and pointer types.
*, /, %
Multiplication, division, and modulus. Multiplication and division are defined on integral and floatingpoint types. Modulus is defined on integral types.
++, 
Increment and decrement. When appearing before a variable, the operation is performed before the variable is used in an expression; when appearing after it, the variable’s value is used before the operation takes place.
*
Pointer dereferencing. Defined on pointer types. Same precedence as
++
.
&
Address operator. Defined on variables. Same precedence as ++
.
For debugging C++, GDB implements a use of ‘&’ beyond what is allowed in the C++ language itself: you can use ‘&(&ref)’ to examine the address where a C++ reference variable (declared with ‘&ref’) is stored.

Negative. Defined on integral and floatingpoint types. Same
precedence as ++
.
!
Logical negation. Defined on integral types. Same precedence as
++
.
~
Bitwise complement operator. Defined on integral types. Same precedence as
++
.
., >
Structure member, and pointertostructure member. For convenience,
GDB regards the two as equivalent, choosing whether to dereference a
pointer based on the stored type information.
Defined on struct
and union
data.
.*, >*
Dereferences of pointers to members.
[]
Array indexing. a[i]
is defined as
*(a+i)
. Same precedence as >
.
()
Function parameter list. Same precedence as >
.
::
C++ scope resolution operator. Defined on struct
, union
,
and class
types.
::
Doubled colons also represent the GDB scope operator
(see Expressions). Same precedence as ::
,
above.
If an operator is redefined in the user code, GDB usually attempts to invoke the redefined version instead of using the operator’s predefined meaning.
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