/*********************************************************/
/* Extended Date Functions */
/* */
/* (c) Copyright 1993 by Stan Milam */
/*********************************************************/
date_t to_date( char *string, int type ) {
date_t rv;
struct dt dt = { 0, 0, 0, 0, 0, 0 };
int len, i, mday, yday, month, year;
char wrkbuf[161], **months = full_month;
year = month = yday = mday = 0;
switch ( type ) {
case DDMMCCYY :
i = sscanf(string, "%2d%2d%4d", &mday, &month,
&year);
if ( i != 3 ) return (date_t) -1L;
month--;
break;
case MMDDCCYY :
i = sscanf(string, "%2d%2d%4d", &month, &mday,
&year);
if ( i != 3 ) return (date_t) -1L;
month--;
break;
case GREGDATE :
i = sscanf(string, "%d%*c%d%*c%d", &month, &mday,
&year);
if ( i != 3 ) return (date_t) -1L;
month--;
break;
case MILDATE :
i = sscanf(string,"%d%*c%d%*c%d",&mday, &month, &year);
if ( i != 3) return (date_t) -1L;
month--;
break;
case SPELLDATE :
i = sscanf(string, "%d%*c%3c%*c%d", &mday, wrkbuf,
&year);
if (i != 3) return (date_t) -1L;
for (month = 0, len = 3; month < 12; month++) {
if ( compare( wrkbuf, months[month], len ) == 0 )
break;
}
if ( month == 12 ) return (date_t) -1;
break;
case JULDATE :
len = strlen( string );
if ( len == 5 || len == 7 ) {
len = 3;
sprintf(wrkbuf, "%%%dd%%%dd", len, 3);
i = sscanf(string, wrkbuf, &year, &yday);
if ( i != 2 ) return (date_t) -1L;
yday--;
}
else return (date_t) -1L;
break;
case SYSDATE :
len = strlen( string );
if ( len == 8 || len == 6 ) {
len -= 4;
sprintf(wrkbuf. "%%%dd%%%dd%%%dd", len, 2, 2);
i = sscanf(string, wrkbuf, &year, &month, &mday);
if ( i != 3 ) return (date_t) -1L;
month--;
}
else return ( date_t ) -1L;
break;
default :
return (date_t) -1L;
}
/***********************************************************/
/* If the year is a two digit year, adjust for the century */
/* change. Anything less than 80 is considered to be in */
/* 21st century. */
/***********************************************************/
if ( year < 100 )
year += year < 80 ? 2000 : 1900;
/***********************************************************/
/* Setup and call mkdate() to get the sequential day number*/
/***********************************************************/
dt.dt_year = year;
db.dt_mday = mday;
dt.dt_yday = yday;
dt.dt_month= month;
rv = mkdate( &dt );
return rv;
}
char *date_to_string(char *buffer, date_t day, int type) {
int size;
struct dt *dt;
char wrkbuf[25], *format;
wrkbuf[0] = '\0';
size = sizeof(wrkbuf);
switch ( type ) {
case GREGDATE :
format = "%x";
break;
case MILDATE :
format = "%d/%m/%Y";
break;
case SPELLDATE :
format = "%d-%b-%Y";
break;
case JULDATE :
format = "%Y%j";
break;
case SYSDATE :
format = "%Y%m%d";
break;
case DDMMCCYY :
format = "%d%m%Y";
break;
case MMDDCCYY :
format = "%m%d%Y";
break;
default :
format = NULL;
}
if ( format != NULL ) {
if (( dt = localdate( &day )) != NULL )
strfdate(wrkbuf, size, format, dt);
}
return (strcpy(buffer, wrkbuf));
}
char *to_char(char *buffer, date_t day, int type) {
return date_to_string(buffer, day, type);
}
date_t next_day_of_week( date_t value, int day ) {
date_t rv;
struct dt *dt;
/***********************************************************/
/* See if we have a valid date value. */
/***********************************************************/
if ((dt = localdate( &value )) == NULL )
rv = (date_t) -1L;
else if ( day < SUNDAY || day > SATURDAY )
rv = (date_t) -1L;
else {
/*******************************************************/
/* Compute how many days until the next specifed day of*/
/* the week. Make sure we are within our limits too. */
********************************************************/
rv = (date_t) 7 - dt->dt_wday + day;
if ( rv > (date_t) 7) rv -= (date_t) 7;
rv = rv + value > MAXDATE ? (date_t) -1L : rv + value;
}
return rv;
}
date_t previous_day_of_week( date_t value, int day ) {
date_t rv;
struct dt *dt;
/***********************************************************/
/* Check for a valid date value. */
************************************************************/
if ((dt = localdate( &value )) == NULL)
rv = (date_t) -1L;
else if ( day < SUNDAY || day > SATURDAY )
rv = (date_t) -1L;
else {
********************************************************/
/* Compute the date value for previous specified day */
/* and do sanity check. */
********************************************************/
rv = (date_t) day - dt->dt_wday;
if ( rv > = (date_t) 0 ) rv -= (date_t) 7L;
rv += value;
if ( rv < (date_t) 1L ) rv = (date_t) -1L;
}
return rv;
}
date_t last_day_of_month( date_t value ) {
date_t rv;
struct dt *dt = localdate( &value );
/***********************************************************/
/* See if date value was valid. */
/***********************************************************/
if ( dt == NULL )
rv = (date_t) -1L;
else {
/*******************************************************/
/* Determine last day of the month, compute the */
/* difference and add to the date value. */
/*******************************************************/
rv = month_table[ dt -> dt_month ];
if ( dt -> dt_month == 1 ) rv += dt -> dt_leap_year;
rv = rv - dt -> dt_mday + value;
}
return rv;
}
date_t first_day_of_month( date_t value ) {
date_t rv;
struct dt *dt = localdate( &value );
rv = ( dt == NULL ) ? -1L : (date_t) 1 - dt -> dt_mday + value;
return rv;
}
date_t compute_date(date_t value, int years, int months, int weeks, int days) {
date_t rv; /* Return value */
int ld1, ld2; /* Last days of months */
struct dt *wrk; /* A date structure */
wrk = localdate( &value ); /* Get a date structure */
if ( wrk == NULL ) return (date_t) -1L;
/***********************************************************/
/* Go ahead and compute the weeks and days. */
/***********************************************************/
rv = (weeks * 7) + days;
/***********************************************************/
/* Now compute the months. We may have to adjust the years */
/* value. */
/***********************************************************/
if ( months ) {
if (abs(months) > 11 ) {
years += months / 12;
months = months % 12;
}
/***********************************************************/
/* Now compute the target month and handle wrap-around.*/
/***********************************************************/
months += wrk -> dt_month;
if ( months <0 ) {
months += 12;
years += -1;
}
else if ( months > 11 ) {
months -= 12;
years += 1;
}
/***********************************************************/
/* Now we have to make adjustment if we are on the last */
/* day of the month. For instance if date is 31 May */
/* and we add 1 month the result should be 30 June. */
/***********************************************************/
ld1 = month_table[wrk ->dt_month];
if ( wrk->dt_month == 1 ) ld1 += wrk->dt_leap_year;
if ( wrk->dt_mday == ld1 ) {
ld2 = month_table[months];
if ( months == 1 ) ld2 +=
is_it_a_leap_year(years + wrk->dt_year);
if (1d1 > ld2 ) wrk->dt_mday = ld2;
}
wrk->dt_month = months;
}
wrk->dt_year += years;
/***********************************************************/
/* The following is a fixup in case we started on Feb 29 */
/* and we are computing into another year. */
/***********************************************************/
ld1 = month_table[wrk->dt_month];
if ( wrk->dt_month == 1 ) ld1 +=
is_it_a_leap_year(wrk->dt_year);
if (wrk->dt_mday > ld1) wrk->dt_mday = ld1;
/***********************************************************/
/* Call mkdate( ) to do the work. */
/***********************************************************/
rv += mkdate( wrk );
return rv;
}
/* End of File */