C++ Numbers and Operators

The C++ expression parser supports all forms of C++ expression syntax. The syntax includes all data types (including pointers, floating-point numbers, and arrays) and all C++ unary and binary operators.

Numbers in C++ Expressions

Numbers in C++ expressions are interpreted as decimal numbers, unless you specify them in another manner. To specify a hexadecimal integer, add 0x before the number. To specify an octal integer, add 0 (zero) before the number.

The default debugger radix does not affect how you enter C++ expressions. You cannot directly enter a binary number (except by nesting a MASM expression within the C++ expression).

You can enter a hexadecimal 64-bit value in the xxxxxxxx`xxxxxxxx format. (You can also omit the grave accent ( ` ).) Both formats produce the same value.

You can use the L, U, and I64 suffixes with integer values. The actual size of the number that is created depends on the suffix and the number that you enter. For more information about this interpretation, see a C++ language reference.

The output of the C++ expression evaluator keeps the data type that the C++ expression rules specify. However, if you use this expression as an argument for a command, a cast is always made. For example, you do not have to cast integer values to pointers when they are used as addresses in command arguments. If the expression's value cannot be validly cast to an integer or a pointer, a syntax error occurs.

You can use the 0n (decimal) prefix for some output, but you cannot use it for C++ expression input.

Characters and Strings in C++ Expressions

You can enter a character by surrounding it with single quotation marks ( ' ). The standard C++ escape characters are permitted.

You can enter string literals by surrounding them with double quotation marks ( " ). You can use \" as an escape sequence within such a string. However, strings have no meaning to the expression evaluator.

Symbols in C++ Expressions

In a C++ expression, each symbol is interpreted according to its type. Depending on what the symbol refers to, it might be interpreted as an integer, a data structure, a function pointer, or any other data type. If you use a symbol that does not correspond to a C++ data type (such as an unmodified module name) within a C++ expression, a syntax error occurs.

If the symbol might be ambiguous, you can add a module name and an exclamation point ( ! ) or only an exclamation point before the symbol. For more information about symbol recognition, see Symbol Syntax and Symbol Matching.

You can use a grave accent ( ` ) or an apostrophe ( ' ) in a symbol name only if you add a module name and exclamation point before the symbol name.

When you add the < and > delimiters after a template name, you can add spaces between these delimiters.

Operators in C++ Expressions

You can always use parentheses to override precedence rules.

If you enclose part of a C++ expression in parentheses and add two at signs (@@) before the expression, the expression is interpreted according to MASM expression rules. You cannot add a space between the two at signs and the opening parenthesis. The final value of this expression is passed to the C++ expression evaluator as a ULONG64 value. You can also specify the expression evaluator by using @@c++( ... ) or @@masm( ... ).

Data types are indicated as usual in the C++ language. The symbols that indicate arrays ( [ ] ), pointer members ( -> ), UDT members ( . ), and members of classes ( :: ) are all recognized. All arithmetic operators are supported, including assignment and side-effect operators. However, you cannot use the new, delete, and throw operators, and you cannot actually call a function.

Pointer arithmetic is supported and offsets are scaled correctly. Note that you cannot add an offset to a function pointer. (If you have to add an offset to a function pointer, cast the offset to a character pointer first.)

As in C++, if you use operators with invalid data types, a syntax error occurs. The debugger's C++ expression parser uses slightly more relaxed rules than most C++ compilers, but all major rules are enforced. For example, you cannot shift a non-integer value.

You can use the following operators. The operators in each cell take precedence over those in lower cells. Operators in the same cell are of the same precedence and are parsed from left to right. As with C++, expression evaluation ends when its value is known. This ending enables you to effectively use expressions such as ?? myPtr && *myPtr.

OperatorMeaning

Expression // Comment

Ignore all subsequent text

Class :: Member

Class ::~Member

:: Name

Member of class

Member of class (destructor)

Global

Structure . Field

Pointer -> Field

Name [integer]

LValue ++

LValue --

dynamic_cast <type>(Value)

static_cast <type>(Value)

reinterpret_cast <type>(Value)

const_cast <type>(Value)

Field in a structure

Field in referenced structure

Array subscript

Increment (after evaluation)

Decrement (after evaluation)

Typecast (always performed)

Typecast (always performed)

Typecast (always performed)

Typecast (always performed)

(type) Value

sizeof value

sizeof( type )

++ LValue

-- LValue

~ Value

! Value

Value

+ Value

& LValue

* Value

Typecast (always performed)

Size of expression

Size of data type

Increment (before evaluation)

Decrement (before evaluation)

Bit complement

Not (Boolean)

Unary minus

Unary plus

Address of data type

Dereference

Structure . * Pointer

Pointer -> * Pointer

Pointer to member of structure

Pointer to member of referenced structure

Value * Value

Value / Value

Value % Value

Multiplication

Division

Modulus

Value + Value

Value - Value

Addition

Subtraction

Value << Value

Value >> Value

Bitwise shift left

Bitwise shift right

Value < Value

Value <= Value

Value > Value

Value >= Value

Less than (comparison)

Less than or equal (comparison)

Greater than (comparison)

Greater than or equal (comparison)

Value == Value

Value != Value

Equal (comparison)

Not equal (comparison)

Value & Value

Bitwise AND

Value ^ Value

Bitwise XOR (exclusive OR)

Value | Value

Bitwise OR

Value && Value

Logical AND

Value || Value

Logical OR

LValue =Value

LValue *= Value

LValue /= Value

LValue %=Value

LValue +=Value

LValue -= Value

LValue <<= Value

LValue >>= Value

LValue &= Value

LValue |= Value

LValue ^= Value

Assign

Multiply and assign

Divide and assign

Modulo and assign

Add and assign

Subtract and assign

Shift left and assign

Shift right and assign

AND and assign

OR and assign

XOR and assign

Value ? Value : Value

Conditional evaluation

Value , Value

Evaluate all values, and then discard all except the rightmost value

 

Registers and Pseudo-Registers in C++ Expressions

You can use registers and pseudo-registers within C++ expressions. You must add an at sign ( @ ) before the register or pseudo-register.

The expression evaluator automatically performs the proper cast. Actual registers and integer-value pseudo-registers are cast to ULONG64. All addresses are cast to PUCHAR, $thread is cast to ETHREAD*, $proc is cast to EPROCESS*, $teb is cast to TEB*, and $peb is cast to PEB*.

You cannot change a register or pseudo-register by an assignment or side-effect operator. You must use the r (Registers) command to change these values.

For more information about registers and pseudo-registers, see Register Syntax and Pseudo-Register Syntax.

Macros in C++ Expressions

You can use macros within C++ expressions. You must add a number sign (#) before the macros.

You can use the following macros. These macros have the same definitions as the Microsoft Windows macros with the same name. (The Windows macros are defined in Winnt.h.)

MacroReturn Value

#CONTAINING_RECORD(Address, Type, Field)

Returns the base address of an instance of a structure, given the type of the structure and the address of a field within the structure.

#FIELD_OFFSET(Type, Field)

Returns the byte offset of a named field in a known structure type.

#RTL_CONTAINS_FIELD (Struct, Size, Field)

Indicates whether the given byte size includes the desired field.

#RTL_FIELD_SIZE(Type, Field)

Returns the size of a field in a structure of known type, without requiring the type of the field.

#RTL_NUMBER_OF(Array)

Returns the number of elements in a statically sized array.

#RTL_SIZEOF_THROUGH_FIELD(Type, Field)

Returns the size of a structure of known type, up through and including a specified field.

 

 

 

Send comments about this topic to Microsoft

Show:
© 2015 Microsoft