HP gnu source-level debugger 5992-4701 Expressions is 0 for false and non-zero for true, As ++

==, !=	Equality and inequality. Defined on scalar types. The value of these
	expressions is 0 for false and non-zero 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 non-zero for true.
<<, >>	left shift, and right shift. Defined on integral types.
@	The GDB “artificial array” operator (see “Expressions” (page 83)).
+, -	Addition and subtraction. Defined on integral types, floating-point
	types and pointer types.
*, /, %	Multiplication, division, and modulus. Multiplication and division
	are defined on integral and floating-point 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 value of the variable 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)' (or, if
	you prefer, simply '&&ref') to examine the address where a C++
	reference variable (declared with '&ref') is stored.
-	Negative. Defined on integral and floating-point 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 pointer-to-structure 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 pointers to members.
[]	Array indexing. a[i] is defined as *(a+i). Same precedence as
	->.
()	Function parameter list. Same precedence as ->.

9.4 Supported languages 107