C alternative tokens
| C standard library |
|---|
| General topics |
| Miscellaneous headers |
C alternative tokens refer to a set of alternative spellings of common operators in the C programming language. They are implemented as a group of macro constants in the C standard library in the iso646.h header. The tokens were added to the standard in a 1995 amendment to the C90 standard.
The alternative tokens allow programmers to use C language bitwise and logical operators which could otherwise be hard to type on some international and non-QWERTY keyboards. The name of the header file they are implemented in refers to the ISO/IEC 646 standard, a 7-bit character set with a number of regional variations, some of which have accented characters in place of the punctuation marks used by C operators.
The macros
The iso646.h header defines the following 11 macros as stated below:
| Macro | Defined as |
|---|---|
and | && |
and_eq | &= |
bitand | & |
bitor | | |
compl | ~ |
not | ! |
not_eq | != |
or | || |
or_eq | |= |
xor | ^ |
xor_eq | ^= |
C++
The above-mentioned identifiers are operator keywords in the ISO C++ programming language and do not require the inclusion of a header file. For consistency, the C++98 standard provides the header <ciso646>. However the latter file has no effect, being empty.[1] Notwithstanding some compilers, such as Microsoft Visual C++, do require the header to be included in order to use these identifiers.
See also
References
- ↑ Lischner, Ray (2003). C++ in a Nutshell. O'Reilly Media. p. 212. ISBN 0-596-00298-X.
External links
- : alternative spellings – Base Definitions Reference, The Single UNIX® Specification, Issue 7 from The Open Group