Alternative operator representations
C++ (and C) source code may be written in any non-ASCII 7-bit character set that includes the ISO 646/ECMA-6 invariant character set. However, several C++ operators and punctuators require characters that are outside of the ISO 646 codeset: {, }, [, ], #, \, ^, |, ^. To be able to use character encodings where some or all of these symbols do not exist, C++ defines two kinds of alternatives: additional keywords that correspond to the operators that use these characters and special combinations of two or three ISO 646 compatible characters that are interpreted as if they were a single non-ISO 646 character.
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[edit] Alternative keywords
There are alternative spellings for several operators defined as keywords in the C++ standard.
Primary | Alternative |
---|---|
&& | and |
&= | and_eq |
& | bitand |
| | bitor |
~ | compl |
! | not |
!= | not_eq |
|| | or |
|= | or_eq |
^ | xor |
^= | xor_eq |
[edit] Compatibility with C
The same words are defined in the C programming language in the include file <iso646.h> as macros. Because in C++ these are language keywords, the C++ version of <iso646.h>, as well as <ciso646>, does not define anything.
[edit] Digraphs and trigraphs
The following combinations of two and three characters (digraphs and trigraphs) are valid substitutions for their respective primary characters:
Primary | Digraph | Trigraph |
---|---|---|
{ | <% | ??< |
} | %> | ??> |
[ | <: | ??( |
] | :> | ??) |
# | %: | ??= |
\ | ??/ | |
^ | ??' | |
| | ??! | |
~ | ??- |
[edit] Keywords
and, and_eq, bitand, bitor, compl, not, not_eq, or, or_eq, xor, xor_eq
[edit] Example
The following example demonstrates the use of several alternative keywords:
%:include <iostream> int main(int argc, char *argv<::>) <% if (argc > 1 and argv<:1:> not_eq '\0') <% std::cout << "Hello " << argv<:1:> << '\n'; %> %>