mktime

Header File

time.h

Category

Time and Date Routines

Prototype

time_t mktime(struct tm *t);

Description

Converts time to calendar format.

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, tm_min, tm_hour, tm_mday, and tm_mon 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.

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

Return Value

On success, mktime returns calendar time as described above.

On error (if the calendar time cannot be represented), mktime returns -1.

Example

Copy Code

#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 a 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 weekday field of the structure */
    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;
}

Portability

POSIX	Win32	ANSI C	ANSI C++
+	+	+	+

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