The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition

2.12 Data Types

All of the data types used by various functions are defined by the implementation. The following table describes some of these types. Other types referenced in the description of a function, not mentioned here, can be found in the appropriate header for that function.

Defined Type

Description

cc_t

Type used for terminal special characters.

clock_t

Integer or real-floating type used for processor times, as defined in the ISO C standard.

clockid_t

Used for clock ID type in some timer functions.

dev_t

Arithmetic type used for device numbers.

DIR

Type representing a directory stream.

div_t

Structure type returned by the div() function.

FILE

Structure containing information about a file.

glob_t

Structure type used in pathname pattern matching.

fpos_t

Type containing all information needed to specify uniquely every position within a file.

gid_t

Integer type used for group IDs.

iconv_t

Type used for conversion descriptors.

id_t

Integer type used as a general identifier; can be used to contain at least the largest of a pid_t, uid_t, or gid_t.

ino_t

Unsigned integer type used for file serial numbers.

key_t

Arithmetic type used for XSI interprocess communication.

ldiv_t

Structure type returned by the ldiv() function.

mode_t

Integer type used for file attributes.

mqd_t

Used for message queue descriptors.

nfds_t

Integer type used for the number of file descriptors.

nlink_t

Integer type used for link counts.

off_t

Signed integer type used for file sizes.

pid_t

Signed integer type used for process and process group IDs.

pthread_attr_t

Used to identify a thread attribute object.

pthread_cond_t

Used for condition variables.

pthread_condattr_t

Used to identify a condition attribute object.

pthread_key_t

Used for thread-specific data keys.

pthread_mutex_t

Used for mutexes.

pthread_mutexattr_t

Used to identify a mutex attribute object.

pthread_once_t

Used for dynamic package initialization.

pthread_rwlock_t

Used for read-write locks.

pthread_rwlockattr_t

Used for read-write lock attributes.

pthread_t

Used to identify a thread.

ptrdiff_t

Signed integer type of the result of subtracting two pointers.

regex_t

Structure type used in regular expression matching.

regmatch_t

Structure type used in regular expression matching.

rlim_t

Unsigned integer type used for limit values, to which objects of type int and off_t can be cast without loss of value.

sem_t

Type used in performing semaphore operations.

sig_atomic_t

Integer type of an object that can be accessed as an atomic entity, even in the presence of asynchronous interrupts.

sigset_t

Integer or structure type of an object used to represent sets of signals.

size_t

Unsigned integer type used for size of objects.

speed_t

Type used for terminal baud rates.

ssize_t

Signed integer type used for a count of bytes or an error indication.

suseconds_t

Signed integer type used for time in microseconds.

tcflag_t

Type used for terminal modes.

time_t

Integer or real-floating type used for time in seconds, as defined in the ISO C standard.

timer_t

Used for timer ID returned by the timer_create() function.

uid_t

Integer type used for user IDs.

useconds_t

Unsigned integer type used for time in microseconds.

va_list

Type used for traversing variable argument lists.

wchar_t

Integer type whose range of values can represent distinct codes for all members of the largest extended character set specified by the supported locales

wctype_t

Scalar type which represents a character class descriptor.

wint_t

Integer type capable of storing any valid value of wchar_t or WEOF.

wordexp_t

Structure type used in word expansion.


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