<s>
C	B-Language
alternative	I-Language
tokens	I-Language
refer	O
to	O
a	O
set	O
of	O
alternative	O
spellings	O
of	O
common	O
operators	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
They	O
are	O
implemented	O
as	O
a	O
group	O
of	O
macro	O
constants	O
in	O
the	B-Language
C	I-Language
standard	I-Language
library	I-Language
in	O
the	O
iso646.h	B-Language
header	O
.	O
</s>
<s>
The	O
tokens	O
were	O
created	O
by	O
Bjarne	O
Stroustrup	O
for	O
the	O
pre-standard	O
C++	B-Language
language	I-Language
and	O
were	O
added	O
to	O
the	O
C	B-Language
standard	O
in	O
a	O
1995	O
amendment	O
to	O
the	O
C90	O
standard	O
via	O
library	O
to	O
avoid	O
the	O
breakage	O
of	O
existing	O
code	O
.	O
</s>
<s>
The	O
alternative	O
tokens	O
allow	O
programmers	O
to	O
use	O
C	B-Language
language	I-Language
bitwise	O
and	O
logical	O
operators	O
which	O
could	O
otherwise	O
be	O
hard	O
to	O
type	O
on	O
some	O
international	O
and	O
non-QWERTY	O
keyboards	O
.	O
</s>
<s>
The	O
name	O
of	O
the	O
header	O
file	O
they	O
are	O
implemented	O
in	O
refers	O
to	O
the	O
ISO/IEC	O
646	O
standard	O
,	O
a	O
7-bit	O
character	O
set	O
with	O
a	O
number	O
of	O
regional	O
variations	O
,	O
some	O
of	O
which	O
have	O
accented	O
characters	O
in	O
place	O
of	O
the	O
punctuation	O
marks	O
used	O
by	O
C	B-Language
operators	I-Language
.	O
</s>
<s>
The	O
iso646.h	B-Language
header	O
defines	O
the	O
following	O
11	O
macros	O
as	O
stated	O
below	O
:	O
</s>
<s>
The	O
above-mentioned	O
identifiers	O
are	O
operator	B-Language
keywords	I-Language
in	O
the	O
ISO	B-Language
C++	I-Language
programming	I-Language
language	I-Language
and	O
do	O
not	O
require	O
the	O
inclusion	O
of	O
a	O
header	O
file	O
.	O
</s>
<s>
For	O
consistency	O
,	O
the	O
C++98	O
standard	O
provides	O
the	O
header	O
<ciso646>	O
.	O
</s>
<s>
Some	O
compilers	O
,	O
such	O
as	O
Microsoft	B-Application
Visual	I-Application
C++	I-Application
have	O
,	O
at	O
least	O
in	O
the	O
past	O
,	O
required	O
the	O
header	O
to	O
be	O
included	O
in	O
order	O
to	O
use	O
these	O
identifiers	O
unless	O
a	O
compiler	O
flag	O
is	O
set	O
.	O
</s>
