Where is strftime(.....)?

[Ingo Feulner]

In article <1990Aug11.230626.2706 at zoo.toronto.edu>, henry at zoo.toronto.edu (Henry Spencer) writes:
> In article <2048 at ux.acs.umn.edu> edh at ux.acs.umn.edu (Eric D. Hendrickson) writes:
> >In the standard library in K&R (ANSI) on page 256 there is a very nice
> >looking procedure for formatting the current time into whatever form you
> >like.  It doesn't seem to be present on this system, or on a local Sparc.
> 
> Many systems are not yet ANSI-compliant.
Hope that will change in the near future...
> 
> I don't know of any redistributable strftime() implementation.

Here is one. It comes with a public domain C compiler named Sozobon C (for
the Amiga), so I think I can post this.

-Enjoy, Ingo.

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/*
 *  STRFTIME.C
 */

#include <time.h>
#include <string.h>
#include <stddef.h>

static char *AbMonth[12] = { "Jan","Feb","Mar","Apr","May","Jun","Jul",
			     "Aug","Sep","Oct","Nov","Dec"
			    };

static char *FuMonth[12] = { "January", "February", "March", "April", "May",
			     "June", "July", "August", "September", "October",
			     "November", "December"
			    };

static char *AbDow[12] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };

static char *FuDow[12] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
			   "Friday", "Saturday"
			};


size_t
strftime(buf, max, fmt, tm)
char *buf;
size_t max;
const char *fmt;
const struct tm *tm;
{
    short i = 0;

    buf[i] = 0;

    while (*fmt) {
	char *ptr;

	i += strlen(buf + i);

	if (*fmt != '%') {
	    buf[i++] = *fmt++;
	    continue;
	}
	ptr = buf + i;
	fmt += 2;
	switch(fmt[-1]) {
	case '%':
	    strcpy(ptr, "%");
	    break;
	case 'a':   /*  abbreviated name for dow    */
	    strcpy(ptr, AbDow[tm->tm_wday]);
	    break;
	case 'A':   /*  full name for dow           */
	    strcpy(ptr, FuDow[tm->tm_wday]);
	    break;
	case 'b':   /*  abbreviated name for month  */
	    strcpy(ptr, AbMonth[tm->tm_mon]);
	    break;
	case 'B':   /*  full name for month         */
	    strcpy(ptr, FuMonth[tm->tm_mon]);
	    break;
	case 'c':   /*  default rep for date & time */
	    sprintf(ptr, "%s %s %02d %02d:%02d:%02d %d",
		AbDow[tm->tm_wday], AbMonth[tm->tm_mon], tm->tm_mday,
		tm->tm_hour, tm->tm_min, tm->tm_sec, tm->tm_year + 1900
	    );
	    break;
	case 'd':   /*  day of month as integer 01-31   */
	    sprintf(ptr, "%02d", tm->tm_mday);
	    break;
	case 'H':   /*  hour as integer 00-23       */
	    sprintf(ptr, "%02d", tm->tm_hour);
	    break;
	case 'I':   /*  hour as integer 01-12       */
	    sprintf(ptr, "%02d", (tm->tm_hour % 12) + 1);
	    break;
	case 'j':   /*  day of year as int 001-366  */
	    sprintf(ptr, "%03d", tm->tm_yday);
	    break;
	case 'm':   /*  month as integer 01-12      */
	    sprintf(ptr, "%02d", tm->tm_mon);
	    break;
	case 'M':   /*  minute as integer 00-59     */
	    sprintf(ptr, "%02d", tm->tm_min);
	    break;
	case 'p':   /*  'AM' or 'PM'                */
	    if (tm->tm_hour >= 12) {
		strcpy(ptr, "PM");
	    } else {
		strcpy(ptr, "AM");
	    }
	    break;
	case 'S':   /*  the second as an int 00-59  */
	    sprintf(ptr, "%02d", tm->tm_sec);
	    break;
	case 'U':   /*  week of year as int 00-53, regard sunday as first day in week   */
	    {
		int bdiw = tm->tm_yday - tm->tm_wday;	/* beginning of week */
		if (bdiw < 0)
		    bdiw = 0;
		else
		    bdiw = bdiw / 7;
		sprintf(ptr, "%02d", bdiw);
	    }
	    break;
	case 'w':   /*  day of week as int 0-6, sunday == 0 */
	    sprintf(ptr, "%d", tm->tm_wday);
	    break;
	case 'W':   /*  day of week as int 0-6, monday == 0 */
	    {
		int dowmon = tm->tm_wday - 1;
		if (dowmon < 0)
		    dowmon += 7;
		sprintf(ptr, "%d", dowmon);
	    }
	    break;
	case 'x':   /*  the locale's default rep for date   */
	    sprintf(ptr, "%s %s %02d",
		AbDow[tm->tm_wday], AbMonth[tm->tm_mon], tm->tm_mday
	    );
	    break;
	case 'X':   /*  the locale's default rep for time   */
	    sprintf(ptr, "%02d:%02d:%02d",
		tm->tm_hour, tm->tm_min, tm->tm_sec
	    );
	    break;
	case 'y':   /*  year within the century 00-99       */
	    sprintf(ptr, "%02d", tm->tm_year % 100);
	    break;
	case 'Y':   /*  the full year, including century    */
	    sprintf(ptr, "%04d", tm->tm_year + 1900);
	    break;
	case 'Z':   /*  the name of the time zone or ""     */
	    strcpy(ptr, "");
	    break;
	default:
	    strcpy(ptr, "%?");
	    break;
	}
    }
    i += strlen(buf + i);
    return((size_t)i);
}

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--
                     Ingo Feulner - alf at xenon.stgt.sub.org
     Wolfacher Weg 22 - 7030 Boeblingen - (+49) 7031 272691 - West Germany
                    Love your enemies. It'll make 'em crazy.
                          AMIGA - the only way to go!