NAME | SYNOPSIS | DESCRIPTION | SEE ALSO
#include <limits.h>
The header <limits.h> is a list of minimal magnitude limitations imposed by a specific implementation of the operating system.
| _ARG_MAX32 | 1048320 | /* max length of arguments to exec 32-bit program */ |
| _ARG_MAX64 | 2096640 | /* max length of arguments to exec 64-bit program */ |
| CHAR_BIT | 8 | /* max # of bits in a char */ |
| CHAR_MAX | 255 | /* max value of a char */ |
| CHAR_MIN | 0 | /* 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*/ |
| DBL_MIN | 2.2250738585072014E-308 | /* min decimal value of a double*/ |
| FCHR_MAX | 1048576 | /* historical default file size limit in bytes */ |
| FLT_DIG | 6 | /* digits of precision of a float */ |
| FLT_MAX | 3.40282347e+38F | /* max decimal value of a float */ |
| FLT_MIN | 1.17549435E-38F | /* min decimal value of a float */ |
| INT_MAX | 2147483647 | /* max value of an int */ |
| INT_MIN | (-2147483647-1) | /* min value of an int */ |
| LINK_MAX | 1000 | /* max # of links to a single file */ |
| LOGNAME_MAX | 8 | /* max # of characters in a login name */ |
| LONG_BIT | 32 | /* # of bits in a long */ |
| LONG_MAX | 2147483647L | /* max value of a long int if _ILP32 defined */ |
| 9223372036854775807L | /* max value of a long int if _LP64 defined */ | |
| LONG_MIN | (-2147483647-1L) | /* min value of a long int if _ILP32 defined */ |
| (-9223372036854775807L-1L) | /* min value of a long int if _LP64 defined */ | |
| 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 | 255 | /* max # of bytes in a message string */ |
| NZERO | 20 | /* default process priority */ |
| OPEN_MAX | 20 | /* max # of files a process can have open */ |
| PASS_MAX | 8 | /* max # of characters in a password */ |
| PATH_MAX | 1024 | /* max # of characters in a path name */ |
| PID_MAX | 999999 | /* max value for a process ID */ |
| PIPE_BUF | 5120 | /* max # bytes atomic in write to a pipe */ |
| PIPE_MAX | 5120 | /* max # bytes written to a pipe in a write */ |
| 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" */ |
| 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 | 2147483647 | /* max value for a user or group ID */ |
| UINT_MAX | 4294967295 | /* max value of an "unsigned int" */ |
| ULONG_MAX | 4294967295UL | /* max value of an "unsigned long int" if _ILP32 defined */ |
| 18446744073709551615UL | /* max value of an "unsigned long int" if _LP64 defined */ | |
| 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-conforming application (see standards(5)). 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 */ |
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO