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Defined in header <ctime> | ||
std::time_t mktime(std::tm* time); | ||
Converts local calendar time to a time since epoch as astd::time_t object.time->tm_wday andtime->tm_yday are ignored. The values intime are permitted to be outside their normal ranges.
A negative value oftime->tm_isdst causesmktime to attempt to determine if Daylight Saving Time was in effect.
If the conversion is successful, thetime object is modified. All fields oftime are updated to fit their proper ranges.time->tm_wday andtime->tm_yday are recalculated using information available in other fields.
Contents |
| time | - | pointer to astd::tm object specifying local calendar time to convert |
Time since epoch as astd::time_t object on success or-1 iftime cannot be represented as astd::time_t object.
If thestd::tm object was obtained fromstd::get_time or the POSIXstrptime, the value oftm_isdst is indeterminate, and needs to be set explicitly before callingmktime.
Construct a local time explicitly.
#include <ctime>#include <iomanip>#include <iostream>#include <sstream> int main(){ setenv("TZ","/usr/share/zoneinfo/America/Los_Angeles",1);// POSIX-specific std::tm tm{};// Zero initialise tm.tm_year=2020-1900;// 2020 tm.tm_mon=2-1;// February tm.tm_mday=15;// 15th tm.tm_hour=10; tm.tm_min=15; tm.tm_isdst=0;// Not daylight savingstd::time_t t= std::mktime(&tm);std::tm local=*std::localtime(&t); std::cout<<"local: "<<std::put_time(&local,"%c %Z")<<'\n';}
Possible output:
local: Sat Feb 15 10:15:00 2020 PST
| converts time since epoch to calendar time expressed as local time (function)[edit] | |
C documentation formktime | |
