👤
Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:
Select Section of Man Page:
Select Man Page Repository:

Linux 2.6 - man page for stdint.h (linux section 7posix)

<stdint.h>(P)			    POSIX Programmer's Manual			    <stdint.h>(P)

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  con-
       stants.

       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 imple-
       mentation 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 corre-
       sponding 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  environ-
		 ment.

	       * 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  implementa-
       tion  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 inte-
       ger 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				    <stdint.h>(P)


All times are GMT -4. The time now is 05:07 AM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
×
UNIX.COM Login
Username:
Password:  
Show Password