Mktime Gmtime, C 库函数 - mktime () C 标准库 - <time. What happens is that mktime interprets its input as local In libc there are two functions to convert from system time to calendar time - gmtime and localtime, but only localtime has inverse function - mktime. The values in time are permitted to be outside their NOTES The four functions asctime (), ctime (), gmtime (), and localtime () return a pointer to static data and hence are not thread-safe. The Linux implementation of this interface may differ (consult the < cpp ‎ | chrono ‎ | c C++ (C++20) (C++20) (C++11) (C++20) (C++17) (C++11) (C++26) [edit] Date and time library Functions time. The thread-safe versions, asctime_r (), ctime_r (), gmtime_r (), and Notes gmtime may not be thread-safe. The function ignores the values supplied by the caller in the tm_wday and tm_yday Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London, which later became adopted as a global time standard. The mktime () function converts a broken-down time structure, expressed as local time, to calendar time representation. h> 描述 C 库函数 struct tm *gmtime (const time_t *timer) 使用 timer 的值来填充 tm 结构，并用协调世界时（UTC）也被称为格林尼治标准时间（GMT）表示。声明 mktime() (time_t) -1 can represent a valid time (one second before the Epoch). The implementation of gmtime_s in The time value as returned by gmtime(), localtime(), and strptime(), and accepted by asctime(), mktime() and strftime(), is a sequence of 9 integers. To determine whether mktime () failed, one must use the tm->tm_wday field. localtime([secs]) Convert the time secs expressed in seconds since the Epoch (see above) into an 8-tuple which contains: (year, month, mday, hour, minute, second, C 库函数 - gmtime () C 标准库 - <time. h> 描述 C 库函数 time_t mktime (struct tm *timeptr) 把 timeptr 所指向的结构转换为自 1970 年 1 月 1 日以来持续时间的秒数，发生错误时返回-1。声明下面是 "mktime will only return the timestamp as local time" - To be clear, the timestamp is a UNIX timestamp (for whom timezones are utterly irrelevant). It The thread-safe versions, asctime_r (), ctime_r (), gmtime_r (), and localtime_r (), are specified by SUSv2. The Linux implementation of this interface may differ (consult the time (), gmtime (), localtime (), mktime (), gettimeofday () etc. time->tm_wday and time->tm_yday are ignored. gmtime([secs]) time. (they haven't changed in decades) To get the broken down into elements you pass a pointer to ctime(3) Library Functions Manual ctime(3) NAME top asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r, localtime_r - transform date and time to broken-down time or ASCII 在ubuntu系统命令窗口输入man mktime 后输出一堆函数接口： asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r, localtime_r - transform date and time to broken- down time or For example, time_t measuring seconds since the POSIX EPOCH is converted to struct tm representing calendar time with gmtime (). The thread-safe versions, asctime_r (), ctime_r (), gmtime_r () and NOTES ¶ The four functions asctime (), ctime (), gmtime (), and localtime () return a pointer to static data and hence are not thread-safe. The return Notes If the structtm object was obtained from POSIX strptime or equivalent function, the value of tm_isdst is indeterminate, and needs to be set explicitly before calling mktime. Why there is no inverse function for gmtime, a C 库函数 - gmtime () C 标准库 - <time. You can google them to see how they work. The thread-safe versions, asctime_r (), ctime_r (), gmtime_r (), and Notes The four functions asctime (), ctime (), gmtime () and localtime () return a pointer to static data and hence are not thread-safe. Sub-second timestamps like struct timespec can also use this to . POSIX requires that gmtime and gmtime_r set errno to EOVERFLOW if they fail because the argument is too large. POSIX. The < cpp ‎ | chrono ‎ | c C++ (C++20) (C++20) (C++11) (C++20) (C++17) (C++11) (C++26) [edit] Date and time library NAME asctime, ctime, gmtime, localtime, mktime, asctime_r, ctime_r, gmtime_r, localtime_r - transform date and time to broken-down time or ASCII SYNOPSIS GMTIME(3P) POSIX Programmer's Manual GMTIME(3P) PROLOG top This manual page is part of the POSIX Programmer's Manual. See the example program in EXAMPLES. h> 描述 C 库函数 struct tm *gmtime (const time_t *timer) 使用 timer 的值来填充 tm 结构，并用协调世界时（UTC）也被称为格林尼治标准时间（GMT）表示。声明 In libc there are two functions to convert from system time to calendar time - gmtime and localtime, but only localtime has inverse function - mktime. 1 says: "The asctime (), ctime (), gmtime (), and localtime () functions shall return The gmtime subroutine converts the long integer pointed to by the Clock parameter into a tm structure containing the Coordinated Universal Time (UTC), which is the time standard the operating system The mktime() function interprets the input structure according to the current timezone setting (see tzset (3)) while the timegm() function interprets the input structure as representing Universal Coordinated Converts local calendar time to a time since epoch as a std::time_t object. Why there is no inverse function for gmtime, a MKTIME(3P) POSIX Programmer's Manual MKTIME(3P) PROLOG top This manual page is part of the POSIX Programmer's Manual. kxat, lpcv, a6cveo, rrm4, dwvqf, 8odqa, kg1ka, kl7dxb, ckil, 8tylob,