<s>
In	O
the	O
C	B-Language
programming	I-Language
language	I-Language
,	O
data	O
types	O
constitute	O
the	O
semantics	O
and	O
characteristics	O
of	O
storage	O
of	O
data	O
elements	O
.	O
</s>
<s>
They	O
are	O
expressed	O
in	O
the	O
language	O
syntax	O
in	O
form	O
of	O
declarations	O
for	O
memory	B-General_Concept
locations	I-General_Concept
or	O
variables	O
.	O
</s>
<s>
The	O
C	B-Language
language	I-Language
provides	O
basic	O
arithmetic	O
types	O
,	O
such	O
as	O
integer	O
and	O
real	O
number	O
types	O
,	O
and	O
syntax	O
to	O
build	O
array	O
and	O
compound	O
types	O
.	O
</s>
<s>
Headers	O
for	O
the	B-Language
C	I-Language
standard	I-Language
library	I-Language
,	O
to	O
be	O
used	O
via	O
include	B-Language
directives	I-Language
,	O
contain	O
definitions	O
of	O
support	O
types	O
,	O
that	O
have	O
additional	O
properties	O
,	O
such	O
as	O
providing	O
storage	O
with	O
an	O
exact	O
size	O
,	O
independent	O
of	O
the	O
language	O
implementation	O
on	O
specific	O
hardware	O
platforms	O
.	O
</s>
<s>
The	O
C	B-Language
language	I-Language
provides	O
the	O
four	O
basic	O
arithmetic	O
type	O
specifiers	O
char	O
,	O
int	O
,	O
float	O
and	O
double	O
,	O
and	O
the	O
modifiers	O
signed	O
,	O
unsigned	O
,	O
short	O
,	O
and	O
long	O
.	O
</s>
<s>
8	O
%c	O
CHAR_MIN	O
/	O
CHAR_MAX	O
n/a	O
signed	O
char	O
Of	O
the	O
same	O
size	O
as	O
char	O
,	O
but	O
guaranteed	O
to	O
be	O
signed	O
.	O
</s>
<s>
8	O
%c	O
(	O
or	O
%hhi	O
for	O
numerical	O
output	O
)	O
SCHAR_MIN	O
/	O
SCHAR_MAX	O
n/a	O
unsigned	O
char	O
Of	O
the	O
same	O
size	O
as	O
char	O
,	O
but	O
guaranteed	O
to	O
be	O
unsigned	O
.	O
</s>
<s>
8	O
%c	O
(	O
or	O
%hhu	O
for	O
numerical	O
output	O
)	O
0	O
/	O
UCHAR_MAX	O
n/a	O
shortshort	O
intsigned	O
shortsigned	O
short	O
int	O
Short	O
signed	O
integer	O
type	O
.	O
</s>
<s>
16	O
%i	O
or	O
%d	B-Language
INT_MIN	O
/	O
INT_MAX	O
none	O
unsignedunsigned	O
int	O
Basic	O
unsigned	O
integer	O
type	O
.	O
</s>
<s>
Specified	O
since	O
the	O
C99	B-Language
version	O
of	O
the	O
standard	O
.	O
</s>
<s>
Specified	O
since	O
the	O
C99	B-Language
version	O
of	O
the	O
standard	O
.	O
</s>
<s>
long	B-Language
double	I-Language
Real	O
floating-point	O
type	O
,	O
usually	O
mapped	O
to	O
an	O
extended	B-Algorithm
precision	I-Algorithm
floating-point	O
number	O
format	O
.	O
</s>
<s>
It	O
can	O
be	O
either	O
x86	O
extended-precision	B-Algorithm
floating-point	I-Algorithm
format	I-Algorithm
(	O
80	O
bits	O
,	O
but	O
typically	O
96	O
bits	O
or	O
128	O
bits	O
in	O
memory	O
with	O
padding	B-Application
bytes	I-Application
)	O
,	O
the	O
non-IEEE	O
"	O
double-double	O
"	O
(	O
128	O
bits	O
)	O
,	O
IEEE	O
754	O
quadruple-precision	O
floating-point	O
format	O
(	O
128	O
bits	O
)	O
,	O
or	O
the	O
same	O
as	O
double	O
.	O
</s>
<s>
See	O
the	B-Language
article	I-Language
on	I-Language
long	I-Language
double	I-Language
for	O
details	O
.	O
</s>
<s>
This	O
holds	O
true	O
for	O
platforms	O
as	O
diverse	O
as	O
1990s	O
SunOS4	O
Unix	O
,	O
Microsoft	B-Application
MS-DOS	I-Application
,	O
modern	O
Linux	B-Application
,	O
and	O
Microchip	O
MCC18	O
for	O
embedded	O
8-bit	O
PIC	O
microcontrollers	B-Architecture
.	O
</s>
<s>
Various	O
rules	O
in	O
the	O
C	B-Language
standard	O
make	O
unsigned	O
char	O
the	O
basic	O
type	O
used	O
for	O
arrays	O
suitable	O
to	O
store	O
arbitrary	O
non-bit-field	O
objects	O
:	O
its	O
lack	O
of	O
padding	O
bits	O
and	O
trap	O
representations	O
,	O
the	O
definition	O
of	O
object	O
representation	O
,	O
and	O
the	O
possibility	O
of	O
aliasing	O
.	O
</s>
<s>
The	O
only	O
requirement	O
is	O
that	O
long	B-Language
double	I-Language
is	O
not	O
smaller	O
than	O
double	O
,	O
which	O
is	O
not	O
smaller	O
than	O
float	O
.	O
</s>
<s>
The	O
C99	B-Language
standard	I-Language
includes	O
new	O
real	O
floating-point	O
types	O
float_t	O
and	O
double_t	O
,	O
defined	O
in	O
<math.h>	O
.	O
</s>
<s>
These	O
types	O
may	O
be	O
wider	O
than	O
long	B-Language
double	I-Language
.	O
</s>
<s>
C99	B-Language
also	O
added	O
complex	O
types	O
:	O
float	O
_Complex	O
,	O
double	O
_Complex	O
,	O
long	B-Language
double	I-Language
_Complex	O
.	O
</s>
<s>
C99	B-Language
added	O
a	O
boolean	O
(	O
true/false	O
)	O
type	O
_Bool	O
.	O
</s>
<s>
This	O
behavior	O
exists	O
to	O
avoid	O
integer	B-Error_Name
overflows	I-Error_Name
in	O
implicit	O
narrowing	O
conversions	O
.	O
</s>
<s>
The	O
C	B-Language
language	I-Language
specification	O
includes	O
the	O
s	O
size_t	O
and	O
ptrdiff_t	O
to	O
represent	O
memory-related	O
quantities	O
.	O
</s>
<s>
Both	O
of	O
these	O
types	O
are	O
defined	O
in	O
the	O
<stddef.h>	O
header	O
(	O
cstddef	O
in	O
C++	O
)	O
.	O
</s>
<s>
The	O
maximum	O
size	O
of	O
size_t	O
is	O
provided	O
via	O
SIZE_MAX	O
,	O
a	O
macro	O
constant	O
which	O
is	O
defined	O
in	O
the	O
<stdint.h>	O
header	O
(	O
cstdint	O
header	O
in	O
C++	O
)	O
.	O
</s>
<s>
Information	O
about	O
the	O
actual	O
properties	O
,	O
such	O
as	O
size	O
,	O
of	O
the	O
basic	O
arithmetic	O
types	O
,	O
is	O
provided	O
via	O
macro	O
constants	O
in	O
two	O
headers	O
:	O
<limits.h> header (climits header in C++ )  defines macros for integer types and <float.h>	O
header	O
(	O
cfloat	O
header	O
in	O
C++	O
)	O
defines	O
macros	O
for	O
floating-point	O
types	O
.	O
</s>
<s>
DECIMAL_DIG	O
(	O
C99	B-Language
)	O
–	O
minimum	O
number	O
of	O
decimal	O
digits	O
such	O
that	O
any	O
number	O
of	O
the	O
widest	O
supported	O
floating-point	O
type	O
can	O
be	O
represented	O
in	O
decimal	O
with	O
a	O
precision	O
of	O
DECIMAL_DIG	O
digits	O
and	O
read	O
back	O
in	O
the	O
original	O
floating-point	O
type	O
without	O
changing	O
its	O
value	O
.	O
</s>
<s>
The	O
C99	B-Language
standard	I-Language
includes	O
definitions	O
of	O
several	O
new	O
integer	O
types	O
to	O
enhance	O
the	O
portability	O
of	O
programs	O
.	O
</s>
<s>
The	O
new	O
types	O
are	O
especially	O
useful	O
in	O
embedded	B-Architecture
environments	I-Architecture
where	O
hardware	O
usually	O
supports	O
only	O
several	O
types	O
and	O
that	O
support	O
varies	O
between	O
different	O
environments	O
.	O
</s>
<s>
All	O
new	O
types	O
are	O
defined	O
in	O
<inttypes.h> header (cinttypes header in C++ )  and also are available at <stdint.h>	O
header	O
(	O
cstdint	O
header	O
in	O
C++	O
)	O
.	O
</s>
<s>
The	O
<inttypes.h> header (cinttypes in C++ )  provides features that enhance the functionality of the types defined in the <stdint.h>	O
header	O
.	O
</s>
<s>
It	O
defines	O
macros	O
for	O
printf	B-Language
format	I-Language
string	I-Language
and	O
scanf	B-Language
format	I-Language
string	I-Language
specifiers	O
corresponding	O
to	O
the	O
types	O
defined	O
in	O
<stdint.h>	O
and	O
several	O
functions	O
for	O
working	O
with	O
the	O
intmax_t	O
and	O
uintmax_t	O
types	O
.	O
</s>
<s>
This	O
header	O
was	O
added	O
in	O
C99	B-Language
.	O
</s>
<s>
The	O
memory	B-General_Concept
address	I-General_Concept
of	O
the	O
first	O
member	O
must	O
be	O
the	O
same	O
as	O
the	O
address	O
of	O
structure	O
itself	O
.	O
</s>
<s>
Since	O
C99	B-Language
,	O
a	O
structure	O
may	O
also	O
end	O
with	O
a	O
flexible	B-Language
array	I-Language
member	I-Language
.	O
</s>
<s>
A	O
structure	O
containing	O
a	O
pointer	O
to	O
a	O
structure	O
of	O
its	O
own	O
type	O
is	O
commonly	O
used	O
to	O
build	O
linked	B-Application
data	I-Application
structures	I-Application
:	O
</s>
<s>
Function	B-Language
pointers	I-Language
allow	O
referencing	O
functions	O
with	O
a	O
particular	O
signature	O
.	O
</s>
<s>
Function	B-Language
pointers	I-Language
are	O
invoked	O
by	O
name	O
just	O
like	O
normal	O
function	O
calls	O
.	O
</s>
<s>
Function	B-Language
pointers	I-Language
are	O
separate	O
from	O
pointers	O
and	O
void	O
pointers	O
.	O
</s>
<s>
The	O
aforementioned	O
types	O
can	O
be	O
characterized	O
further	O
by	O
type	B-Language
qualifiers	I-Language
,	O
yielding	O
a	O
qualified	O
type	O
.	O
</s>
<s>
and	O
C11	O
,	O
there	O
are	O
four	O
type	B-Language
qualifiers	I-Language
in	O
standard	O
C	B-Language
:	O
const	O
(	O
C89	O
)	O
,	O
volatile	B-Operating_System
(	O
C89	O
)	O
,	O
restrict	B-Language
(	O
C99	B-Language
)	O
and	O
_Atomic	O
(	O
C11	O
)	O
the	O
latter	O
has	O
a	O
private	O
name	O
to	O
avoid	O
clashing	O
with	O
user	O
names	O
,	O
but	O
the	O
more	O
ordinary	O
name	O
atomic	O
can	O
be	O
used	O
if	O
the	O
<stdatomic.h>	O
header	O
is	O
included	O
.	O
</s>
<s>
Of	O
these	O
,	O
const	O
is	O
by	O
far	O
the	O
best-known	O
and	O
most	O
used	O
,	O
appearing	O
in	O
the	O
standard	B-Library
library	I-Library
and	O
encountered	O
in	O
any	O
significant	O
use	O
of	O
the	O
C	B-Language
language	I-Language
,	O
which	O
must	O
satisfy	O
const-correctness	O
.	O
</s>
