mktime

Converts time to calendar format.

Defined in header <time.h>

Syntax

#include <time.h>
time_t mktime(struct tm *t);

Portability

Remarks

Converts the time in the structure pointed to by t into a calendar time with the same format used by the time function. The original values of the fields tm_sec, tmjnin, tmjiour, tmjnday, and tmjnon are not restricted to the ranges described in the tm structure. If the fields are not in their proper ranges, they are adjusted. Values for fields tm_wday and tm_yday are computed after the other fields have been adjusted. If the calender time cannot be represented, mktime returns -1.

The allowable range of calender times is Jan 1 1970 00:00:00 to Jan 19 2038 03:14:07.

Return value

See Remarks.

See also

• localtime
• strftime
• time

Example

#include <stdio.h>
#include <time.h>

char *wday[] =    "Sunday", "Monday", "Tuesday", "Wednesday", Thursday",  "Friday",
                 "Saturday ", "Unknown"};
int main (void)
struct tm time_check;
int year, month, day;
/* input year, month,  and day to find the weekday for */
printf ("Year:  ");
scanf ("%d", &year);
printf ("Month: ");
scanf ("%d", &month);
printf ("Day:   ");
scanf {"%d", &day);
/* load the time_check  structure with the data */
time_check.tm_year  = year - 1900;
time_check.tm_mon   = month - 1;
time_check.tm_mday  = day;
time_check.tm_hour  = 0
time_check.tm_min   = 0
time_check.tm_sec   = 1
time_check.tm_isdst  - -1;
/* call mktime to  fill in the structure's v/eekday field */
if  (mktime(&time_check) -= -1)
   time_check.tm_wday  = 7;

/* print out the day  of the week */
printf ("That day is a %s\n", wday[time_check.tm_wday]);
return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

• cppreference (search)
• Microsoft C runtime (search)

These are search links, not yet checked by hand.

Stable link: /3.1/time.h/mktime/ · short form /3.1/mktime/