Keywords in Standard Mode

C++ has added several new keywords. If you use any of these as identifiers, you get numerous and sometimes bizarre error messages. (It is quite difficult to determine when a programmer has used a keyword as an identifier, and the compiler error messages might not be helpful in such cases.)

Most of the new keywords can be disabled with a compiler option, as shown in the following table. Some are logically related, and get enabled or disabled in a group.

Table 3-1 Keywords in Standard Mode

Keyword	Compiler option to disable
bool, true, false	-features=no%bool
explicit	-features=no%explicit
export	-features=no%export
mutable	-features=no%mutable
namespace, using	cannot disable
typename	cannot disable
and, and_eq, bitand, compl, not, not_eq, or, bitor, xor, xor_eq	-features=no%altspell (see note below)

---

Note -

Alternative spellings for special tokens: The addendum to the ISO C standard introduced the C standard header <iso646.h>, which defined new macros to generate the special tokens. The C++ standard has introduced these spellings directly as reserved words. (When the alternative spellings are enabled, including <iso646.h> in your program has no net effect.) The meaning of these tokens is shown in the following table.

---

Table 3-2 Alternative Token Spellings

Token	Spelling
&&	and
&&=	and_eq
&	bitand
~	compl
!	not
!=	not_eq
||	or
|	bitor
~	xor
~=	xor_eq