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. |