limits --
header file for implementation-specific constants
Synopsis
#include <limits.h>
Description
The header file limits.h
is a list of minimal magnitude limitations
imposed by a specific implementation of the operating system.
The values listed below are subject to change.
ARG_MAX
10240
max length of arguments to exec
CHAR_BIT
8
max # of bits in a "char"
CHAR_MAX
127
max value of a "char"
CHAR_MIN
-128
min value of a "char"
CHILD_MAX
25
max # of processes per user id
CLK_TCK
_sysconf(3)
clock ticks per second
DBL_DIG
15
digits of precision of a "double"
DBL_MAX
1.7976931348623157E+308
max decimal value of a "double"
FLT_DIG
6
digits of precision of a "float"
FLT_MAX
3.40282347e+38F
max decimal value of a "float"
INT_MAX
0x7fffffff
max value of an "int"
INT_MIN
(-INT_MAX-1)
min value of an "int"
LINK_MAX
1000
max # of links to a single file
LLONG_MAX
0x7fffffffffffffff
max value of a "signed long long"
LLONG_MIN
(-LLONG_MAX-1)
min value of a "signed long long"
LOGNAME_MAX
8
max # of characters in a login
name
LONG_BIT
32
# of bits in a "long"
LONG_MAX
0x7fffffffffffffff
max value of a "long int"
LONG_MIN
(-LONG_MAX-1)
min value of a "long int"
MAX_CANON
256
max bytes in a line for canonical
processing
MAX_INPUT
512
max size of a char input buffer
MB_LEN_MAX
5
max # of bytes in a multibyte
character
NAME_MAX
14
max # of characters in a file name
NGROUPS_MAX
16
max # of groups for a user
NL_ARGMAX
9
max value of "digit" in calls to
the NLS printf() and scanf()
NL_LANGMAX
14
max # of bytes in a LANG name
NL_MSGMAX
32767
max message number
NL_NMAX
1
max # of bytes in N-to-1 mapping
characters
NL_SETMAX
255
max set number
NL_TEXTMAX
4096
max # of bytes in a message string
NZERO
20
default process priority
OPEN_MAX
60
max # of files a process can have
open
PASS_MAX
80
max # of characters in a password
BC_BASE_MAX
99
max obase values bc utility allows
BC_SCALE_MAX
99
max scale value bc utility allows
BC_DIM_MAX
2048
max # of elements allowed in a
bc utility array
BC_STRING_MAX
1000
max length of a bc utility string
constant
COLL_WEIGHTS_MAX
2
max # weights assignable to an
entry of LC_COLLATE
EXPR_NEST_MAX
32
max # of expressions allowed to be
nested within parentheses by the
expr utility
LINE_MAX
2048
max byte length of the utility's
input line when the utility is
processing text files
RE_DUP_MAX
255
max # repeated occurrences of a
regexp permitted when using m,n
CHARCLASS_NAME_MAX
100
max # bytes character class
name can have
PATH_MAX
1024
max # of characters in a path name
PID_MAX
30000
max value for a process ID
PIPE_BUF
5120
max # bytes atomic in write to
a pipe
SCHAR_MAX
127
max value of a "signed char"
SCHAR_MIN
-128
min value of a "signed char"
SHRT_MAX
32767
max value of a "short int"
SHRT_MIN
-32768
min value of a "short int"
SSIZE_MAX
INT_MAX
max value of an "int"
STD_BLK
1024
# bytes in a physical I/O block
SYS_NMLN
257
4.0 size of utsname elements
also defined in sys/utsname.h
SYSPID_MAX
1
max pid of system processes
TMP_MAX
17576
max # of unique names generated
by tmpnam
UCHAR_MAX
255
max value of an "unsigned char"
UID_MAX
60002
max value for a user or group ID
UINT_MAX
0xffffffff
max value of an "unsigned int"
ULLONG_MAX
0xffffffffffffffff
max value of an "unsigned long long"
ULONG_MAX
0xffffffffffffffff
max value of an "unsigned long
int"
USHRT_MAX
65535
max value of an "unsigned short
int"
USI_MAX
4294967295
max decimal value of an
"unsigned"
WORD_BIT
32
# of bits in a "word" or "int"
The following
POSIX
definitions are the most
restrictive values to be used by a
POSIX
conformant application. Conforming implementations shall
provide values at least this large.
_POSIX_ARG_MAX
4096
max length of arguments to exec
_POSIX_CHILD_MAX
6
max # of processes per user ID
_POSIX_LINK_MAX
8
max # of links to a single file
_POSIX_MAX_CANON
255
max # of bytes in a line of input
_POSIX_MAX_INPUT
255
max # of bytes in terminal
input queue
_POSIX_NAME_MAX
14
# of bytes in a filename
_POSIX_NGROUPS_MAX
0
max # of groups in a process
_POSIX_OPEN_MAX
16
max # of files a process can have open
_POSIX_PATH_MAX
255
max # of characters in a pathname
_POSIX_PIPE_BUF
512
max # of bytes atomic in write
to a pipe
_POSIX_SSIZE_MAX
32767
min value stored in object of
type ssize_t
_POSIX_STREAM_MAX
8
min number of streams (stdio)
that one process can have open at a time
_POSIX_TZNAME_MAX
3
max number of bytes supported
for name of a timezone (not the TZ variable)