/* * print out the number of seconds since the epoch, the current time, * and a pbreakdown of both the current local and UTC times * * Matt Bishop * -- May 22 2024 original program */ #include <stdio.h> #include <stdlib.h> #include <time.h> #include <errno.h> /* * translate number of the day of the week into a 3-char string * handle unknown and unexpected problems */ char *dow(int n) { /* get the day corresponding to n, which is to be 0-6 */ switch(n){ case 0: return("Sun"); case 1: return("Mon"); case 2: return("Tue"); case 3: return("Wed"); case 4: return("Thu"); case 5: return("Fri"); case 6: return("Sat"); default: return("???"); /* some other value, unknown day */ } /* Can't happen */ fprintf(stderr, "dow: went past switch with all returns\n"); exit(1); } /* * translate number of the month into a 3-char string * handle unknown and unexpected problems */ char *moy(int n) { /* get the month corresponding to n, which is to be 0-11 */ switch(n){ case 0: return("Jan"); case 1: return("Feb"); case 2: return("Mar"); case 3: return("Apr"); case 4: return("May"); case 5: return("Jun"); case 6: return("Jul"); case 7: return("Aug"); case 8: return("Sep"); case 9: return("Oct"); case 10: return("Nov"); case 11: return("Dec"); default: return("???"); /* some other value. unknown month */ } /* Can't happen */ fprintf(stderr, "dow: went past switch with all returns\n"); exit(1); } /* * print all the details about the time */ void prtime(struct tm *parts) { #ifdef TIME_ZOME printf("\tTime zone: %s (%d seconds offset from UTC time 0\n", parts->tm_zone, parts->tm_gmtoff); #endif printf("\tIs it daylight savings time? %s\n", parts->tm_isdst ? "yes" : "no"); printf("\tDay of the year: %d\n", parts->tm_yday); printf("\tDay of the week: %d (%s)\n", parts->tm_wday, dow(parts->tm_wday)); printf("\tYear (-1900): %d (%d)\n", parts->tm_year, parts->tm_year + 1900); printf("\tMonth: %d (%s)\n", parts->tm_mon, moy(parts->tm_mon)); printf("\tDay of the month: %d\n", parts->tm_mday); printf("\tHour: %d\n", parts->tm_hour); printf("\tMinute: %d\n", parts->tm_min); printf("\tSecond: %d\n", parts->tm_sec); } /* * we're off! The main routine */ int main(void) { time_t tick; /* seconds since the epoch */ char *tock; /* points to (ctime) date and time */ struct tm *parts; /* broken down time */ /* * get the internal representation of time */ if ((tick = time(NULL)) == -1){ perror("time"); return(1); } printf("time in seconds is %ld\n", (long) tick); /* * print it as an intelligible character string */ if ((tock = ctime(&tick)) == NULL){ perror("ctime"); return(1); } /* now let's break it down */ if ((parts = localtime(&tick)) == NULL){ perror("localtime"); return(1); } printf("Here are the details of the local time:\n"); prtime(parts); /* and here it is in UTC */ if ((parts = gmtime(&tick)) == NULL){ perror("gmtime"); return(1); } printf("Here are the details of the UTC time:\n"); prtime(parts); /* th-th-that's all, folks! -- Porky Pig */ return(0); }
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ECS 36A, Programming & Problem Solving Version of April 2, 2024 at 12:13PM
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You can get the raw source code here. |