The mktime() function is defined in the time.h header file. According to the local time zone, it helps to convert the structure pointed to by timeptr into a time_t value.
time_t mktime(struct tm *timeptr); #where timeptr should be a pointer
The mktime() function takes a single parameter 'timeptr' which is a pointer to the structure which contains a calendar time.The components of calendar time are,
struct tm {
int tm_sec; /* seconds, range 0 to 59 */
int tm_min; /* minutes, range 0 to 59 */
int tm_hour; /* hours, range 0 to 23 */
int tm_mday; /* day of the month, range 1 to 31 */
int tm_mon; /* month, range 0 to 11 */
int tm_year; /* The number of years since 1900 */
int tm_wday; /* day of the week, range 0 to 6 */
int tm_yday; /* day in the year, range 0 to 365 */
int tm_isdst; /* daylight saving time */
};
Parameter | Description | Required / Optional |
---|---|---|
timeptr | the pointer to a time_t value representing a calendar time | Required |
The function returns time_t value corresponding to the calendar time passed as argument.
Input | Return Value |
---|---|
if parameter | time_t value |
On failure | -1 |
#include <stdio.h>
#include <time.h>
int main()
{
int out;
struct tm info;
char buf[80];
info.tm_year = 2001 - 1900; info.tm_m
info.tm_mday = 4;
info.tm_hour = 0;
info.tm_min = 0;
info.tm_sec = 1;
info.tm_isdst = -1;
out = mktime(&info);
if( out == -1 ) {
printf("Error: unable to make time using mktime\n");
} else {
strftime(buf, sizeof(buf), "%c", &info );
printf(buf);
}
return(0);
}
Output:
Wed Jul 4 00:00:01 2001
#include <stdio.h>
#include <time.h>
int main (){
struct tm t_info;
time_t t_format;
t_info.tm_year = 2008-1900; t_info.tm_m
t_info.tm_mday = 1;
t_info.tm_hour = 0;
t_info.tm_min = 0;
t_info.tm_sec = 1;
t_info.tm_isdst = 0;
t_format = mktime(&t_info);
printf(ctime(&t_format));
return 0;
}
Output:
Tue Jan 1 00:00:01 2008