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The C and C++ Include Header Files
cat -n /usr/include/time.h
1 /* Copyright (C) 1991-2026 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <https://www.gnu.org/licenses/>. */ 17 18 /* 19 * ISO C99 Standard: 7.23 Date and time <time.h> 20 */ 21 22 #ifndef _TIME_H 23 #define _TIME_H 1 24 25 #include <features.h> 26 27 #define __need_size_t 28 #define __need_NULL 29 #include <stddef.h> 30 31 #if __GLIBC_USE (ISOC23) 32 # define __STDC_VERSION_TIME_H__ 202311L 33 #endif 34 35 /* This defines CLOCKS_PER_SEC, which is the number of processor clock 36 ticks per second, and possibly a number of other constants. */ 37 #include <bits/time.h> 38 39 /* Many of the typedefs and structs whose official home is this header 40 may also need to be defined by other headers. */ 41 #include <bits/types/clock_t.h> 42 #include <bits/types/time_t.h> 43 #include <bits/types/struct_tm.h> 44 45 #if defined __USE_POSIX199309 || defined __USE_ISOC11 46 # include <bits/types/struct_timespec.h> 47 #endif 48 49 #ifdef __USE_POSIX199309 50 # include <bits/types/clockid_t.h> 51 # include <bits/types/timer_t.h> 52 # include <bits/types/struct_itimerspec.h> 53 struct sigevent; 54 #endif 55 56 #ifdef __USE_XOPEN2K 57 # ifndef __pid_t_defined 58 typedef __pid_t pid_t; 59 # define __pid_t_defined 60 # endif 61 #endif 62 63 #ifdef __USE_XOPEN2K8 64 # include <bits/types/locale_t.h> 65 #endif 66 67 #ifdef __USE_ISOC11 68 /* Time base values for timespec_get. */ 69 # define TIME_UTC 1 70 #endif 71 #if __GLIBC_USE (ISOC23) 72 # define TIME_MONOTONIC 2 73 # define TIME_ACTIVE 3 74 # define TIME_THREAD_ACTIVE 4 75 #endif 76 77 __BEGIN_DECLS 78 79 /* Time used by the program so far (user time + system time). 80 The result / CLOCKS_PER_SEC is program time in seconds. */ 81 extern clock_t clock (void) __THROW; 82 83 #ifndef __USE_TIME64_REDIRECTS 84 /* Return the current time and put it in *TIMER if TIMER is not NULL. */ 85 extern time_t time (time_t *__timer) __THROW; 86 87 /* Return the difference between TIME1 and TIME0. */ 88 extern double difftime (time_t __time1, time_t __time0); 89 90 /* Return the `time_t' representation of TP and normalize TP. */ 91 extern time_t mktime (struct tm *__tp) __THROW; 92 #else 93 # ifdef __REDIRECT_NTH 94 extern time_t __REDIRECT_NTH (time, (time_t *__timer), __time64); 95 extern double __REDIRECT_NTH (difftime, (time_t __time1, time_t __time0), 96 __difftime64); 97 extern time_t __REDIRECT_NTH (mktime, (struct tm *__tp), __mktime64); 98 # else 99 # define time __time64 100 # define difftime __difftime64 101 # define mktime __mktime64 102 # endif 103 #endif 104 105 /* Format TP into S according to FORMAT. 106 Write no more than MAXSIZE characters and return the number 107 of characters written, or 0 if it would exceed MAXSIZE. */ 108 extern size_t strftime (char *__restrict __s, size_t __maxsize, 109 const char *__restrict __format, 110 const struct tm *__restrict __tp) 111 __THROW __nonnull((1, 3, 4)); 112 113 #ifdef __USE_XOPEN 114 /* Parse S according to FORMAT and store binary time information in TP. 115 The return value is a pointer to the first unparsed character in S. */ 116 extern char *strptime (const char *__restrict __s, 117 const char *__restrict __fmt, struct tm *__tp) 118 __THROW; 119 #endif 120 121 #ifdef __USE_XOPEN2K8 122 /* Similar to the two functions above but take the information from 123 the provided locale and not the global locale. */ 124 125 extern size_t strftime_l (char *__restrict __s, size_t __maxsize, 126 const char *__restrict __format, 127 const struct tm *__restrict __tp, 128 locale_t __loc) __THROW; 129 #endif 130 131 #ifdef __USE_GNU 132 extern char *strptime_l (const char *__restrict __s, 133 const char *__restrict __fmt, struct tm *__tp, 134 locale_t __loc) __THROW; 135 #endif 136 137 138 #ifndef __USE_TIME64_REDIRECTS 139 /* Return the `struct tm' representation of *TIMER 140 in Universal Coordinated Time (aka Greenwich Mean Time). */ 141 extern struct tm *gmtime (const time_t *__timer) __THROW; 142 143 /* Return the `struct tm' representation 144 of *TIMER in the local timezone. */ 145 extern struct tm *localtime (const time_t *__timer) __THROW; 146 147 #else 148 # ifdef __REDIRECT_NTH 149 extern struct tm*__REDIRECT_NTH (gmtime, (const time_t *__timer), __gmtime64); 150 extern struct tm *__REDIRECT_NTH (localtime, (const time_t *__timer), 151 __localtime64); 152 # else 153 # define gmtime __gmtime64 154 # define localtime __localtime64 155 # endif 156 #endif 157 158 159 #if defined __USE_POSIX || __GLIBC_USE (ISOC23) 160 # ifndef __USE_TIME64_REDIRECTS 161 /* Return the `struct tm' representation of *TIMER in UTC, 162 using *TP to store the result. */ 163 extern struct tm *gmtime_r (const time_t *__restrict __timer, 164 struct tm *__restrict __tp) __THROW; 165 166 /* Return the `struct tm' representation of *TIMER in local time, 167 using *TP to store the result. */ 168 extern struct tm *localtime_r (const time_t *__restrict __timer, 169 struct tm *__restrict __tp) __THROW; 170 # else 171 # ifdef __REDIRECT_NTH 172 extern struct tm*__REDIRECT_NTH (gmtime_r, (const time_t *__restrict __timer, 173 struct tm *__restrict __tp), 174 __gmtime64_r); 175 176 extern struct tm*__REDIRECT_NTH (localtime_r, (const time_t *__restrict __t, 177 struct tm *__restrict __tp), 178 __localtime64_r); 179 # else 180 # define gmtime_r __gmtime64_r 181 # define localtime_r __localtime_r 182 # endif 183 # endif 184 #endif /* POSIX || C23 */ 185 186 /* Return a string of the form "Day Mon dd hh:mm:ss yyyy\n" 187 that is the representation of TP in this format. */ 188 extern char *asctime (const struct tm *__tp) __THROW; 189 190 /* Equivalent to `asctime (localtime (timer))'. */ 191 #ifndef __USE_TIME64_REDIRECTS 192 extern char *ctime (const time_t *__timer) __THROW; 193 #else 194 # ifdef __REDIRECT_NTH 195 extern char *__REDIRECT_NTH (ctime, (const time_t *__timer), __ctime64); 196 # else 197 # define ctime __ctime64 198 # endif 199 #endif 200 201 #ifdef __USE_POSIX 202 /* Reentrant versions of the above functions. */ 203 204 /* Return in BUF a string of the form "Day Mon dd hh:mm:ss yyyy\n" 205 that is the representation of TP in this format. */ 206 extern char *asctime_r (const struct tm *__restrict __tp, 207 char *__restrict __buf) __THROW; 208 209 /* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'. */ 210 #ifndef __USE_TIME64_REDIRECTS 211 extern char *ctime_r (const time_t *__restrict __timer, 212 char *__restrict __buf) __THROW; 213 #else 214 # ifdef __REDIRECT_NTH 215 extern char *__REDIRECT_NTH (ctime_r, (const time_t *__restrict __timer, 216 char *__restrict __buf), __ctime64_r); 217 # else 218 # define ctime_r __ctime64_r 219 # endif 220 #endif 221 222 #endif /* POSIX */ 223 224 225 /* Defined in localtime.c. */ 226 extern char *__tzname[2]; /* Current time zone abbreviations. */ 227 extern int __daylight; /* If daylight-saving time is ever in use. */ 228 extern long int __timezone; /* Seconds west of UTC. */ 229 230 231 #ifdef __USE_POSIX 232 /* Same as above. */ 233 extern char *tzname[2]; 234 235 /* Set time conversion information from the TZ environment variable. 236 If TZ is not defined, a locale-dependent default is used. */ 237 extern void tzset (void) __THROW; 238 #endif 239 240 #if defined __USE_MISC || defined __USE_XOPEN 241 extern int daylight; 242 extern long int timezone; 243 #endif 244 245 246 /* Nonzero if YEAR is a leap year (every 4 years, 247 except every 100th isn't, and every 400th is). */ 248 #define __isleap(year) \ 249 ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0)) 250 251 252 #if defined __USE_MISC || __GLIBC_USE (ISOC23) 253 # ifndef __USE_TIME64_REDIRECTS 254 /* Like `mktime', but for TP represents Universal Time, not local time. */ 255 extern time_t timegm (struct tm *__tp) __THROW; 256 # else 257 # ifdef __REDIRECT_NTH 258 extern time_t __REDIRECT_NTH (timegm, (struct tm *__tp), __timegm64); 259 # else 260 # define timegm __timegm64 261 # endif 262 # endif 263 #endif 264 265 266 #ifdef __USE_MISC 267 /* Miscellaneous functions many Unices inherited from the public domain 268 localtime package. These are included only for compatibility. */ 269 270 #ifndef __USE_TIME64_REDIRECTS 271 /* Another name for `mktime'. */ 272 extern time_t timelocal (struct tm *__tp) __THROW; 273 #else 274 # ifdef __REDIRECT_NTH 275 extern time_t __REDIRECT_NTH (timelocal, (struct tm *__tp), __mktime64); 276 # endif 277 #endif 278 279 /* Return the number of days in YEAR. */ 280 extern int dysize (int __year) __THROW __attribute__ ((__const__)); 281 #endif 282 283 284 #ifdef __USE_POSIX199309 285 # ifndef __USE_TIME64_REDIRECTS 286 /* Pause execution for a number of nanoseconds. 287 288 This function is a cancellation point and therefore not marked with 289 __THROW. */ 290 extern int nanosleep (const struct timespec *__requested_time, 291 struct timespec *__remaining); 292 293 /* Get resolution of clock CLOCK_ID. */ 294 extern int clock_getres (clockid_t __clock_id, struct timespec *__res) __THROW; 295 296 /* Get current value of clock CLOCK_ID and store it in TP. */ 297 extern int clock_gettime (clockid_t __clock_id, struct timespec *__tp) 298 __THROW __nonnull((2)); 299 300 /* Set clock CLOCK_ID to value TP. */ 301 extern int clock_settime (clockid_t __clock_id, const struct timespec *__tp) 302 __THROW __nonnull((2)); 303 # else 304 # ifdef __REDIRECT 305 extern int __REDIRECT (nanosleep, (const struct timespec *__requested_time, 306 struct timespec *__remaining), 307 __nanosleep64); 308 extern int __REDIRECT_NTH (clock_getres, (clockid_t __clock_id, 309 struct timespec *__res), 310 __clock_getres64); 311 extern int __REDIRECT_NTH (clock_gettime, (clockid_t __clock_id, struct 312 timespec *__tp), __clock_gettime64) 313 __nonnull((2)); 314 extern int __REDIRECT_NTH (clock_settime, (clockid_t __clock_id, const struct 315 timespec *__tp), __clock_settime64) 316 __nonnull((2)); 317 # else 318 # define nanosleep __nanosleep64 319 # define clock_getres __clock_getres64 320 # define clock_gettime __clock_gettime64 321 # define clock_settime __clock_settime64 322 # endif 323 # endif 324 325 326 # ifdef __USE_XOPEN2K 327 /* High-resolution sleep with the specified clock. 328 329 This function is a cancellation point and therefore not marked with 330 __THROW. */ 331 # ifndef __USE_TIME64_REDIRECTS 332 extern int clock_nanosleep (clockid_t __clock_id, int __flags, 333 const struct timespec *__req, 334 struct timespec *__rem); 335 # else 336 # ifdef __REDIRECT 337 extern int __REDIRECT (clock_nanosleep, (clockid_t __clock_id, int __flags, 338 const struct timespec *__req, 339 struct timespec *__rem), 340 __clock_nanosleep_time64); 341 # else 342 # define clock_nanosleep __clock_nanosleep_time64 343 # endif 344 # endif 345 346 /* Return clock ID for CPU-time clock. */ 347 extern int clock_getcpuclockid (pid_t __pid, clockid_t *__clock_id) __THROW; 348 # endif 349 350 351 /* Create new per-process timer using CLOCK_ID. */ 352 extern int timer_create (clockid_t __clock_id, 353 struct sigevent *__restrict __evp, 354 timer_t *__restrict __timerid) __THROW; 355 356 /* Delete timer TIMERID. */ 357 extern int timer_delete (timer_t __timerid) __THROW; 358 359 /* Set timer TIMERID to VALUE, returning old value in OVALUE. */ 360 # ifndef __USE_TIME64_REDIRECTS 361 extern int timer_settime (timer_t __timerid, int __flags, 362 const struct itimerspec *__restrict __value, 363 struct itimerspec *__restrict __ovalue) __THROW; 364 365 /* Get current value of timer TIMERID and store it in VALUE. */ 366 extern int timer_gettime (timer_t __timerid, struct itimerspec *__value) 367 __THROW; 368 # else 369 # ifdef __REDIRECT_NTH 370 extern int __REDIRECT_NTH (timer_settime, (timer_t __timerid, int __flags, 371 const struct itimerspec *__restrict __value, 372 struct itimerspec *__restrict __ovalue), 373 __timer_settime64); 374 375 extern int __REDIRECT_NTH (timer_gettime, (timer_t __timerid, 376 struct itimerspec *__value), 377 __timer_gettime64); 378 # else 379 # define timer_settime __timer_settime64 380 # define timer_gettime __timer_gettime64 381 # endif 382 # endif 383 384 /* Get expiration overrun for timer TIMERID. */ 385 extern int timer_getoverrun (timer_t __timerid) __THROW; 386 #endif 387 388 389 #ifdef __USE_ISOC11 390 # ifndef __USE_TIME64_REDIRECTS 391 /* Set TS to calendar time based in time base BASE. */ 392 extern int timespec_get (struct timespec *__ts, int __base) 393 __THROW __nonnull ((1)); 394 # else 395 # ifdef __REDIRECT_NTH 396 extern int __REDIRECT_NTH (timespec_get, (struct timespec *__ts, int __base), 397 __timespec_get64) __nonnull ((1)); 398 # else 399 # define timespec_get __timespec_get64 400 # endif 401 # endif 402 #endif 403 404 405 #if __GLIBC_USE (ISOC23) 406 # ifndef __USE_TIME64_REDIRECTS 407 /* Set TS to resolution of time base BASE. */ 408 extern int timespec_getres (struct timespec *__ts, int __base) 409 __THROW; 410 # else 411 # ifdef __REDIRECT_NTH 412 extern int __REDIRECT_NTH (timespec_getres, (struct timespec *__ts, 413 int __base), 414 __timespec_getres64); 415 # else 416 # define timespec_getres __timespec_getres64 417 # endif 418 # endif 419 #endif 420 421 422 #ifdef __USE_XOPEN_EXTENDED 423 /* Set to one of the following values to indicate an error. 424 1 the DATEMSK environment variable is null or undefined, 425 2 the template file cannot be opened for reading, 426 3 failed to get file status information, 427 4 the template file is not a regular file, 428 5 an error is encountered while reading the template file, 429 6 memory allication failed (not enough memory available), 430 7 there is no line in the template that matches the input, 431 8 invalid input specification Example: February 31 or a time is 432 specified that can not be represented in a time_t (representing 433 the time in seconds since 00:00:00 UTC, January 1, 1970) */ 434 extern int getdate_err; 435 436 /* Parse the given string as a date specification and return a value 437 representing the value. The templates from the file identified by 438 the environment variable DATEMSK are used. In case of an error 439 `getdate_err' is set. 440 441 This function is a possible cancellation point and therefore not 442 marked with __THROW. */ 443 extern struct tm *getdate (const char *__string); 444 #endif 445 446 #ifdef __USE_GNU 447 /* Since `getdate' is not reentrant because of the use of `getdate_err' 448 and the static buffer to return the result in, we provide a thread-safe 449 variant. The functionality is the same. The result is returned in 450 the buffer pointed to by RESBUFP and in case of an error the return 451 value is != 0 with the same values as given above for `getdate_err'. 452 453 This function is not part of POSIX and therefore no official 454 cancellation point. But due to similarity with an POSIX interface 455 or due to the implementation it is a cancellation point and 456 therefore not marked with __THROW. */ 457 extern int getdate_r (const char *__restrict __string, 458 struct tm *__restrict __resbufp); 459 #endif 460 461 __END_DECLS 462 463 #endif /* time.h. */
