The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group

 Data Types

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

Defined Type Description
cc_t Type used for terminal special characters.
clock_t Arithmetic type used for processor times.
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 div() function.
FILE A 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 Arithmetic type used for group IDs.
iconv_t Type used for conversion descriptors.
id_t Arithmetic type used as a general identifier; can be used to contain at least the largest of a pid_t, uid_t or a gid_t.
ino_t Arithmetic type used for file serial numbers.
key_t Arithmetic type used for interprocess communication.
ldiv_t Structure type returned by ldiv() function.
mode_t Arithmetic type used for file attributes.
mqd_t Used for message queue descriptors.
nfds_t Integral type used for the number of file descriptors.
nlink_t Arithmetic type used for link counts.
off_t Signed Arithmetic type used for file sizes.
pid_t Signed Arithmetic 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 initialisation.
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 integral 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 arithmetic 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 Integral type of an object that can be accessed as an atomic entity, even in the presence of asynchronous interrupts.
sigset_t Integral or structure type of an object used to represent sets of signals.
size_t Unsigned integral type used for size of objects.
speed_t Type used for terminal baud rates.
ssize_t Arithmetic type used for a count of bytes or an error indication.
suseconds_t A signed arithmetic type used for time in microseconds.
tcflag_t Type used for terminal modes.
time_t Arithmetic type used for time in seconds.
timer_t Used for timer ID returned by timer_create().
uid_t Arithmetic type used for user IDs.
useconds_t Integral type used for time in microseconds.
va_list Type used for traversing variable argument lists.
wchar_t Integral 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 An integral type capable of storing any valid value of wchar_t, or
wordexp_t Structure type used in word expansion.

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Copyright © 1997 The Open Group
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