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NetBSD 6.1.5 - man page for limits (netbsd section 3)

LIMITS(3)			   BSD Library Functions Manual 			LIMITS(3)

     limits -- standard limits

     #include <limits.h>

     The <limits.h> header defines various compile-time and runtime limits.  These can be grouped
     into three categories:

	   1.	Compile-time limits defined in a header file.

	   2.	Runtime system limits that are not associated with a file or directory; see

	   3.	Runtime limits that are associated with a file or directory; see pathconf(2).

     The <limits.h> header has been standardized by at least three entities.

   ISO Limits
     The limits defined by the ISO/IEC 9899:1999 (``ISO C99'') standard are all compile-time lim-
     its.  The numerical (integer) limits are:

	   Constant	  Type			  Minimum value
	   CHAR_BIT	  char			  8
	   SCHAR_MAX	  signed char		  127
	   SCHAR_MIN	  signed char		 -127
	   UCHAR_MAX	  unsigned char 	  255

	   INT_MAX	  int			  32767
	   INT_MIN	  int			 -32767
	   UINT_MAX	  unsigned int		  65535

	   SHRT_MIN	  short 		 -32767
	   SHRT_MAX	  short 		  32767
	   USHRT_MAX	  unsigned short	  65535

	   LONG_MAX	  long int		  2147483647
	   LONG_MIN	  long int		 -2147483647
	   ULONG_MAX	  unsigned long int	  4294967295

	   LLONG_MAX	  long long int 	  9223372036854775807
	   LLONG_MIN	  long long int 	 -9223372036854775807
	   ULLONG_MAX	  unsigned long long int  18446744073709551615

	   MB_LEN_MAX	  -			 1

     All listed limits may vary across machines and operating systems.	The standard guarantees
     only that the implementation-defined values are equal or greater in absolute value to those
     shown.  The values permit a system with 16-bit integers using one's complement arithmetic.

     Depending whether the system defines char as signed or unsigned, the maximum and minimum
     values are:

	   Constant	  Type			 Minimum value
	   CHAR_MAX	  char			 either SCHAR_MAX or UCHAR_MAX
	   CHAR_MIN	  char			 either SCHAR_MIN or 0

     The two special cases, CHAR_BIT and MB_LEN_MAX, define the number of bits in char and the
     maximum number of bytes in a multibyte character constant, respectively.

   POSIX Limits
     The POSIX.1 standard specifies numerous limits related to the operating system.  For each
     limit, a separate constant prefixed with ``_POSIX_'' defines the lowest value that the limit
     is allowed to have on any POSIX compliant system.	For instance, _POSIX_OPEN_MAX defines the
     minimum upper bound permitted by POSIX for the number of files that a single process may
     have open at any time.  This ensures that a portable program can safely reach these limits
     without prior knowledge about the actual limits used in a particular system.

     As the limits are not necessary invariant, pathconf(2) and sysconf(3) should be used to
     determine the actual value of a limit at runtime.	The manual pages of these two functions
     also contain a more detailed description of the limits available in NetBSD.

   XSI Limits
     Also the X/Open System Interface Extension (XSI) specifies few limits.  In NetBSD these are
     limited to LONG_BIT (the number of bits in long), WORD_BIT (the number of bits in a
     ``word''), and few limits related to float and double.

     getconf(1), pathconf(2), sysconf(3), types(3), unistd(3)

     Richard W. Stevens and Stephen A. Rago, Advanced Programming in the UNIX Environment,
     Addison-Wesley, Second Edition, 2005.

BSD					  August 9, 2011				      BSD

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