HP-UX Reference (11i v3 07/02) - 5 Miscellaneous Topics (vol 9)

l
limits(5) limits(5)
NAME
limits - implementation-specific constants
SYNOPSIS
#include <limits.h>
DESCRIPTION
The following symbols are defined in
<limits.h> and are used throughout the descriptive text of this
manual. The column headed HP-UX Value lists the values that application writers should assume for por-
tability across all HP-UX systems.
Symbols after values are interpreted as follows:
+ Actual limit might be greater than specified value on certain HP-UX systems.
++ Actual limit might be greater than value specified in
<limits.h> on certain HP-UX systems.
- Actual limit might be less than the specified value on certain HP-UX systems.
= Actual limit is always equal to the specified value and does not vary across HP-UX systems.
* The name of this limit is defined only if the preprocessor macro _XPG2 is defined, either by the
compilation flag
-D_XPG2,orbya#define directive in the source before <limits.h> is
included in the source.
# The value defined for this limit might not be a compile-time constant. The value defined always
evaluates to an integer expression at run time.
Some of these limits vary with system configuration, and can be determined dynamically by using sys-
conf(2). Others can vary according to file system or device associated with a specific file, and can be deter-
mined with pathconf(2). Others are obsolescent because they are redundant with other limits or not useful
in portable applications. They are provided only for importability of applications from other systems, to
support applications that comply with the X/Open Portability Guide, Issue 2, and for backward compatibil-
ity with earlier versions of HP-UX. The
_XPG2 flag should not be defined in new applications.
By including the <limits.h> file in the compilation an application can test the appropriate limits to
determine whether it can operate on a particular system, or it might even alter its behavior to match the
system to increase its portability across a varying range of limit settings and systems.
Constant Description HP-UX Value Sym
Max length of arguments to exec(2) in bytes,
including environment data
ARG_MAX 5120 +*
Number of bits in a charCHAR_BIT 8 =
Max integer value of a charCHAR_MAX 127 =
Min integer value of a charCHAR_MIN -128 =
Max number of simultaneous processes per user
ID
CHILD_MAX 25 +-*
Number of clock ticks per secondCLK_TCK 50 +#
Digits of precision of a
doubleDBL_DIG 15 +
Max positive value of a doubleDBL_MAX 1.7976931348623157e+308
+
Min positive value of a
doubleDBL_MIN 4.94065645841246544e-324
-
Max file offset in bytes
FCHR_MAX INT_MAX +-*
Digits of precision of a floatFLT_DIG 6 +
Max positive value of a floatFLT_MAX 3.40282346638528860e+38 +
Min positive value of a
floatFLT_MIN 1.40129846432481707e-45 -
Max decimal value of an
intINT_MAX 2147483647 +
Min decimal value of an intINT_MIN -2147483648 -
Max number of characters in a single lineLINE_MAX 2048 =
Max number of links to a single fileLINK_MAX 32 767 +*
236 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007