PROLOG<\/a> This manual page is part of the POSIX Programmer\u2019s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.<\/p>\n mktime \u2014 convert broken-down time into time since the Epoch<\/p>\n #include time_t mktime(struct tm *timeptr<\/i>);<\/p>\n The functionality described on this reference page is aligned with the ISO\u00a0C standard. Any conflict between the requirements described here and the ISO\u00a0C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO\u00a0C standard.<\/p>\n The mktime<\/i>() function shall convert the broken-down time, expressed as local time, in the structure pointed to by timeptr<\/i>, into a time since the Epoch value with the same encoding as that of the values returned by time<\/i>(). The original values of the tm_wday<\/i> and tm_yday<\/i> components of the structure shall be ignored, and the original values of the other components shall not be restricted to the ranges described in A positive or 0 value for tm_isdst<\/i> shall cause mktime<\/i>() to presume initially that Daylight Savings Time, respectively, is or is not in effect for the specified time. A negative value for tm_isdst<\/i> shall cause mktime<\/i>() to attempt to determine whether Daylight Savings Time is in effect for the specified time.<\/p>\n Local timezone information shall be set as though mktime<\/i>() called tzset<\/i>().<\/p>\n The relationship between the tm<\/b> structure (defined in the Upon successful completion, the values of the tm_wday<\/i> and tm_yday<\/i> components of the structure shall be set appropriately, and the other components shall be set to represent the specified time since the Epoch, but with their values forced to the ranges indicated in the The mktime<\/i>() function shall return the specified time since the Epoch encoded as a value of type time_t<\/b>. If the time since the Epoch cannot be represented, the function shall return the value (time_t<\/b>)\u22121 and set errno<\/i> to indicate the error.<\/p>\n The mktime<\/i>() function shall fail if: The result cannot be represented.<\/p>\n The following sections are informative.<\/i><\/p>\n What day of the week is July 4, 2001?<\/p>\n #include struct tm time_str;<\/p>\n char daybuf[20];<\/p>\n int main(void) None.<\/p>\n None.<\/p>\n None.<\/p>\n asctime<\/i>(), clock<\/i>(), ctime<\/i>(), difftime<\/i>(), gmtime<\/i>(), localtime<\/i>(), strftime<\/i>(), strptime<\/i>(), time<\/i>(), tzset<\/i>(), utime<\/i>()<\/p>\n
NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
RETURN VALUE<\/a>
ERRORS<\/a>
EXAMPLES<\/a>
APPLICATION USAGE<\/a>
RATIONALE<\/a>
FUTURE DIRECTIONS<\/a>
SEE ALSO<\/a>
COPYRIGHT<\/a> <\/p>\n
\nPROLOG <\/a> <\/h2>\n
NAME <\/a> <\/h2>\n
SYNOPSIS <\/a> <\/h2>\n
DESCRIPTION <\/a> <\/h2>\n
RETURN VALUE <\/a> <\/h2>\n
ERRORS <\/a> <\/h2>\n
EOVERFLOW<\/b><\/p>\nEXAMPLES <\/a> <\/h2>\n
#include
{
time_str.tm_year = 2001 \u2014 1900;
time_str.tm_mon = 7 \u2014 1;
time_str.tm_mday = 4;
time_str.tm_hour = 0;
time_str.tm_min = 0;
time_str.tm_sec = 1;
time_str.tm_isdst = -1;
if (mktime(&time_str) == -1)
(void)puts(“-unknown-“);
else {
(void)strftime(daybuf, sizeof(daybuf), “%A”, &time_str);
(void)puts(daybuf);
}
return 0;
}<\/p>\nAPPLICATION USAGE <\/a> <\/h2>\n
RATIONALE <\/a> <\/h2>\n
FUTURE DIRECTIONS <\/a> <\/h2>\n
SEE ALSO <\/a> <\/h2>\n