p7-7.c

UNIX程序设计教程

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <errno.h>
void report_time(struct tm *);
static char *wday[7]={"Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
int main(void)
{
    time_t    the_time;
    struct    tm  *tm_time;
    struct    tm  unknown_time = {
    /* sec, min, hour, mday, mon, year, wday, yday, isdst */
       40,  30,  2,    1,    8,   98,   0,    259,  0,
    };
    time (&the_time);                            /*  取当前原始时间  */
    printf (" current raw time is %ld\n", the_time);
    tm_time = gmtime(&the_time);      /*  转换原始时间至GMT分解时  */
    printf (" gmtime gives: \n");
    report_time(tm_time);
    /*  转换原始时间至本地时  */
    tm_time = localtime (&the_time);
    printf (" localtime gives: \n");
    report_time(tm_time);
    /*  转换一个用分解时表示的不存在的日期至原始时间  */
    the_time = mktime (&unknown_time);
    if ( the_time <0 ) 
        printf ("ERROR: mktime() call failed\n");
        else {
        printf (" after calling mktime:\n");
        printf ("     time = %ld\n", the_time);
            report_time(&unknown_time);
            printf ("     weekday: %s   yearday: %d\n",
            wday[unknown_time.tm_wday], unknown_time.tm_yday);
    }
}
void report_time(struct tm *tm_ptr)
{
    printf ("     date: %02d/%02d/%02d\n",
              tm_ptr->tm_year, tm_ptr->tm_mon+1, tm_ptr->tm_mday);
    printf ("     time: %02d:%02d:%02d\n",
              tm_ptr->tm_hour, tm_ptr->tm_min, tm_ptr->tm_sec);
    asctime(tm_ptr);
}