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C/C++ Users Group Library 1996 July
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C-C++ Users Group Library July 1996.iso
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v_11_02
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1102019a
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1992-12-07
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81 lines
/* _Getdst function */
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include "xtime.h"
static int getint(const char *s, int n)
{ /* accumulate digits */
int value;
for (value = 0; 0 <= --n && isdigit(*s); ++s)
value = value * 10 + *s - '0';
return (0 <= n ? -1 : value);
}
Dstrule *_Getdst(const char *s)
{ /* parse DST rules */
const char delim = *s++;
Dstrule *pr, *rules;
if (delim == '\0')
return (NULL);
{ /* buy space for rules */
const char *s1, *s2;
int i;
for (s1 = s, i = 2;
(s2 = strchr(s1, delim)) != NULL; ++i)
s1 = s2 + 1;
if ((rules = (Dstrule *)malloc(sizeof (Dstrule)
* i)) == NULL)
return (NULL);
}
{ /* parse rules */
int year = 0;
for (pr = rules; ; ++pr, ++s)
{ /* parse next rule */
if (*s == '(')
{ /* got a year qualifier */
year = getint(s + 1, 4) - 1900;
if (year < 0 || s[5] != ')')
break; /* invalid year */
s += 6;
}
pr->year = year;
pr->mon = getint(s, 2) - 1, s += 2;
pr->day = getint(s, 2) - 1, s += 2;
if (isdigit(*s))
pr->hour = getint(s, 2), s += 2;
else
pr->hour = 0;
if (12 <= pr->mon || 99 < pr->day
|| 99 < pr->hour)
break; /* invalid month, day, or hour */
if (*s != '+' && *s != '-')
pr->wday = 0;
else if (s[1] < '0' || '6' < s[1])
break; /* invalid week day */
else
{ /* compute week day field */
pr->wday = s[1] == '0' ? 7 : s[1] - '0';
if (*s == '+') /* '-': strictly before */
pr->wday += 7; /* '+': on or after */
s += 2;
}
if (*s == '\0')
{ /* done, terminate list */
(pr + 1)->wday = (unsigned char)-1;
(pr + 1)->year = year;
return (rules);
}
else if (*s != delim)
break;
}
free(rules);
return (NULL);
}
}