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NAME

       stdint.h - integer types

SYNOPSIS

       #include <stdint.h>

DESCRIPTION

       Some  of the functionality described on this reference page extends the
       ISO C standard. Applications shall define the appropriate feature  test
       macro  (see  the  System  Interfaces  volume  of  IEEE Std 1003.1-2001,
       Section 2.2, The Compilation Environment) to enable the  visibility  of
       these symbols in this header.

       The  <stdint.h>  header  shall  declare  sets  of  integer types having
       specified widths, and shall define corresponding  sets  of  macros.  It
       shall   also  define  macros  that  specify  limits  of  integer  types
       corresponding to types defined in other standard headers.

       Note:  The "width" of an integer type is the number  of  bits  used  to
              store its value in a pure binary system; the actual type may use
              more bits than that (for example, a 28-bit type could be  stored
              in  32  bits of actual storage). An N-bit signed type has values
              in the range -2**N-1 or 1-2**N-1 to  2**N-1-1,  while  an  N-bit
              unsigned type has values in the range 0 to 2**N-1.

       Types are defined in the following categories:

        * Integer types having certain exact widths

        * Integer types having at least certain specified widths

        * Fastest integer types having at least certain specified widths

        * Integer types wide enough to hold pointers to objects

        * Integer types having greatest width

       (Some of these types may denote the same type.)

       Corresponding macros specify limits of the declared types and construct
       suitable constants.

       For each type described herein that the  implementation  provides,  the
       <stdint.h>  header  shall  declare  that  typedef  name  and define the
       associated macros. Conversely, for each type described herein that  the
       implementation  does  not  provide,  the  <stdint.h>  header  shall not
       declare that typedef name, nor shall it define the  associated  macros.
       An  implementation shall provide those types described as required, but
       need not provide any of the others (described as optional).

   Integer Types
       When typedef names differing only in the absence  or  presence  of  the
       initial  u  are  defined,  they  shall  denote corresponding signed and
       unsigned types as described in the ISO/IEC 9899:1999 standard,  Section
       6.2.5;  an  implementation  providing  one of these corresponding types
       shall also provide the other.

       In the following descriptions, the  symbol  N  represents  an  unsigned
       decimal integer with no leading zeros (for example, 8 or 24, but not 04
       or 048).

        * Exact-width integer types

       The typedef name int N _t designates a signed integer type  with  width
       N, no padding bits, and a two’s-complement representation. Thus, int8_t
       denotes a signed integer type with a width of exactly 8 bits.

       The typedef name uint N _t designates an  unsigned  integer  type  with
       width  N.  Thus, uint24_t denotes an unsigned integer type with a width
       of exactly 24 bits.

       The following types are required:

       int8_t
       int16_t
       int32_t
       uint8_t
       uint16_t
       uint32_t

       If an implementation provides integer types with  width  64  that  meet
       these  requirements,  then  the  following  types are required: int64_t
       uint64_t

       In particular, this will be the case if any of the following are true:

               * The  implementation   supports   the   _POSIX_V6_ILP32_OFFBIG
                 programming environment and the application is being built in
                 the _POSIX_V6_ILP32_OFFBIG programming environment  (see  the
                 Shell  and  Utilities  volume  of  IEEE Std 1003.1-2001, c99,
                 Programming Environments).

               * The   implementation   supports   the    _POSIX_V6_LP64_OFF64
                 programming environment and the application is being built in
                 the _POSIX_V6_LP64_OFF64 programming environment.

               * The  implementation   supports   the   _POSIX_V6_LPBIG_OFFBIG
                 programming environment and the application is being built in
                 the _POSIX_V6_LPBIG_OFFBIG programming environment.

       All other types of this form are optional.

        * Minimum-width integer types

       The typedef name int_least N _t designates a signed integer type with a
       width  of at least N, such that no signed integer type with lesser size
       has at least the specified width. Thus, int_least32_t denotes a  signed
       integer type with a width of at least 32 bits.

       The  typedef  name  uint_least N _t designates an unsigned integer type
       with a width of at least N, such that no  unsigned  integer  type  with
       lesser  size  has  at  least  the specified width. Thus, uint_least16_t
       denotes an unsigned integer type with a width of at least 16 bits.

       The  following   types   are   required:   int_least8_t   int_least16_t
       int_least32_t int_least64_t uint_least8_t uint_least16_t uint_least32_t
       uint_least64_t

       All other types of this form are optional.

        * Fastest minimum-width integer types

       Each of the following types designates an integer type that is  usually
       fastest  to operate with among all integer types that have at least the
       specified width.

       The designated type is not guaranteed to be fastest for  all  purposes;
       if  the  implementation has no clear grounds for choosing one type over
       another,  it  will  simply  pick  some  integer  type  satisfying   the
       signedness and width requirements.

       The  typedef  name  int_fast N _t designates the fastest signed integer
       type with a width of at least  N.  The  typedef  name  uint_fast  N  _t
       designates  the  fastest unsigned integer type with a width of at least
       N.

       The following types are required: int_fast8_t int_fast16_t int_fast32_t
       int_fast64_t uint_fast8_t uint_fast16_t uint_fast32_t uint_fast64_t

       All other types of this form are optional.

        * Integer types capable of holding object pointers

       The  following  type designates a signed integer type with the property
       that any valid pointer to void can be  converted  to  this  type,  then
       converted  back to a pointer to void, and the result will compare equal
       to the original pointer: intptr_t

       The following  type  designates  an  unsigned  integer  type  with  the
       property  that any valid pointer to void can be converted to this type,
       then converted back to a pointer to void, and the result  will  compare
       equal to the original pointer: uintptr_t

       On  XSI-conformant  systems,  the  intptr_t  and  uintptr_t  types  are
       required;   otherwise, they are optional.

        * Greatest-width integer types

       The  following  type  designates  a  signed  integer  type  capable  of
       representing any value of any signed integer type: intmax_t

       The  following  type  designates  an  unsigned  integer type capable of
       representing any value of any unsigned integer type: uintmax_t

       These types are required.

       Note:  Applications  can  test  for  optional  types   by   using   the
              corresponding limit macro from Limits of Specified-Width Integer
              Types .

   Limits of Specified-Width Integer Types
       The following macros specify the minimum  and  maximum  limits  of  the
       types declared in the <stdint.h> header. Each macro name corresponds to
       a similar type name in Integer Types .

       Each instance of any defined macro shall  be  replaced  by  a  constant
       expression  suitable  for use in #if preprocessing directives, and this
       expression shall have the same type as would an expression that  is  an
       object  of  the  corresponding  type converted according to the integer
       promotions. Its implementation-defined  value  shall  be  equal  to  or
       greater  in  magnitude  (absolute  value)  than the corresponding value
       given below, with the same sign, except where stated to be exactly  the
       given value.

        * Limits of exact-width integer types

           * Minimum values of exact-width signed integer types:

          {INTN_MIN}
                 Exactly -(2 **N-1)

           * Maximum values of exact-width signed integer types:

          {INTN_MAX}
                 Exactly 2**N-1 -1

           * Maximum values of exact-width unsigned integer types:

          {UINTN_MAX}
                 Exactly 2 **N -1

        * Limits of minimum-width integer types

           * Minimum values of minimum-width signed integer types:

          {INT_LEASTN_MIN}
                 -(2 ** N-1 -1)

           * Maximum values of minimum-width signed integer types:

          {INT_LEASTN_MAX}
                 2 ** N-1 -1

           * Maximum values of minimum-width unsigned integer types:

          {UINT_LEASTN_MAX}
                 2 ** N -1

        * Limits of fastest minimum-width integer types

           * Minimum values of fastest minimum-width signed integer types:

          {INT_FASTN_MIN}
                 -(2 ** N-1 -1)

           * Maximum values of fastest minimum-width signed integer types:

          {INT_FASTN_MAX}
                 2 ** N-1 -1

           * Maximum values of fastest minimum-width unsigned integer types:

          {UINT_FASTN_MAX}
                 2 ** N -1

        * Limits of integer types capable of holding object pointers

           * Minimum value of pointer-holding signed integer type:

          {INTPTR_MIN}
                 -(2 ** 15 -1)

           * Maximum value of pointer-holding signed integer type:

          {INTPTR_MAX}
                 2 ** 15 -1

           * Maximum value of pointer-holding unsigned integer type:

          {UINTPTR_MAX}
                 2 ** 16 -1

        * Limits of greatest-width integer types

           * Minimum value of greatest-width signed integer type:

          {INTMAX_MIN}
                 -(2 ** 63 -1)

           * Maximum value of greatest-width signed integer type:

          {INTMAX_MAX}
                 2 ** 63 -1

           * Maximum value of greatest-width unsigned integer type:

          {UINTMAX_MAX}
                 2 ** 64 -1

   Limits of Other Integer Types
       The  following macros specify the minimum and maximum limits of integer
       types corresponding to types defined in other standard headers.

       Each  instance  of  these  macros  shall  be  replaced  by  a  constant
       expression  suitable  for use in #if preprocessing directives, and this
       expression shall have the same type as would an expression that  is  an
       object  of  the  corresponding  type converted according to the integer
       promotions. Its implementation-defined  value  shall  be  equal  to  or
       greater  in  magnitude  (absolute  value)  than the corresponding value
       given below, with the same sign.

        * Limits of ptrdiff_t:

       {PTRDIFF_MIN}
              -65535

       {PTRDIFF_MAX}
              +65535

        * Limits of sig_atomic_t:

       {SIG_ATOMIC_MIN}
              See below.

       {SIG_ATOMIC_MAX}
              See below.

        * Limit of size_t:

       {SIZE_MAX}
              65535

        * Limits of wchar_t:

       {WCHAR_MIN}
              See below.

       {WCHAR_MAX}
              See below.

        * Limits of wint_t:

       {WINT_MIN}
              See below.

       {WINT_MAX}
              See below.

       If sig_atomic_t (see the <signal.h> header)  is  defined  as  a  signed
       integer  type,  the  value of {SIG_ATOMIC_MIN} shall be no greater than
       -127 and the value of {SIG_ATOMIC_MAX}  shall  be  no  less  than  127;
       otherwise,  sig_atomic_t  shall be defined as an unsigned integer type,
       and the  value  of  {SIG_ATOMIC_MIN}  shall  be  0  and  the  value  of
       {SIG_ATOMIC_MAX} shall be no less than 255.

       If  wchar_t  (see the <stddef.h> header) is defined as a signed integer
       type, the value of {WCHAR_MIN} shall be no greater than  -127  and  the
       value  of  {WCHAR_MAX}  shall  be  no less than 127; otherwise, wchar_t
       shall be defined  as  an  unsigned  integer  type,  and  the  value  of
       {WCHAR_MIN}  shall  be  0 and the value of {WCHAR_MAX} shall be no less
       than 255.

       If wint_t (see the <wchar.h> header) is defined  as  a  signed  integer
       type,  the  value of {WINT_MIN} shall be no greater than -32767 and the
       value of {WINT_MAX} shall be no  less  than  32767;  otherwise,  wint_t
       shall  be  defined  as  an  unsigned  integer  type,  and  the value of
       {WINT_MIN} shall be 0 and the value of {WINT_MAX} shall be no less than
       65535.

   Macros for Integer Constant Expressions
       The  following  macros  expand to integer constant expressions suitable
       for initializing objects that have integer types corresponding to types
       defined  in  the  <stdint.h>  header.  Each macro name corresponds to a
       similar  type  name  listed  under  Minimum-width  integer  types   and
       Greatest-width integer types.

       Each  invocation  of  one  of  these  macros shall expand to an integer
       constant expression suitable for use in #if  preprocessing  directives.
       The  type  of  the  expression  shall  have  the  same type as would an
       expression that is  an  object  of  the  corresponding  type  converted
       according to the integer promotions.  The value of the expression shall
       be that of the argument.

       The argument in any instance of these macros shall be a decimal, octal,
       or  hexadecimal  constant  with a value that does not exceed the limits
       for the corresponding type.

        * Macros for minimum-width integer constant expressions

       The macro INTN_C( value) shall expand to an integer constant expression
       corresponding  to  the  type  int_least N _t. The macro UINTN_C( value)
       shall expand to an integer constant  expression  corresponding  to  the
       type  uint_least N _t. For example, if uint_least64_t is a name for the
       type unsigned long long,  then  UINT64_C(0x123)  might  expand  to  the
       integer constant 0x123ULL.

        * Macros for greatest-width integer constant expressions

       The  following  macro  expands to an integer constant expression having
       the  value  specified  by  its  argument   and   the   type   intmax_t:
       INTMAX_C(value)

       The  following  macro  expands to an integer constant expression having
       the  value  specified  by  its  argument  and   the   type   uintmax_t:
       UINTMAX_C(value)

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       The  <stdint.h>  header  is  a  subset  of the <inttypes.h> header more
       suitable for use in freestanding environments, which might not  support
       the  formatted  I/O  functions.  In some environments, if the formatted
       conversion support is not wanted, using  this  header  instead  of  the
       <inttypes.h> header avoids defining such a large number of macros.

       As a consequence of adding int8_t, the following are true:

        * A byte is exactly 8 bits.

        * {CHAR_BIT}   has  the  value  8,  {SCHAR_MAX}  has  the  value  127,
          {SCHAR_MIN} has the value -127 or  -128,  and  {UCHAR_MAX}  has  the
          value 255.

FUTURE DIRECTIONS

       typedef  names  beginning  with  int  or uint and ending with _t may be
       added to the types  defined  in  the  <stdint.h>  header.  Macro  names
       beginning  with  INT  or  UINT and ending with _MAX, _MIN, or _C may be
       added to the macros defined in the <stdint.h> header.

SEE ALSO

       <inttypes.h> , <signal.h> , <stddef.h> , <wchar.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .