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PsL Monthly 1993 December
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PSL Monthly Shareware CD-ROM (December 1993).iso
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STRFTIME.C
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C/C++ Source or Header
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1991-09-23
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10KB
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340 lines
/**
*
* strftime.c
*
* implements the ansi c function strftime()
*
* written 6 september 1989 by jim nutt
* released into the public domain by jim nutt
*
* modified 21-Oct-89 by Rob Duff
*
**/
#include <stddef.h> /* for size_t */
#include <stdarg.h> /* for va_arg */
#include <time.h> /* for struct tm */
/*
** The following line should be appended to TIME.H.
** Also copy size_t define from STRING.H.
*/
size_t strftime(char *s, size_t maxs, const char *f, const struct tm *t);
static char *aday[] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
static char *day[] = {
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"
};
static char *amonth[] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
static char *month[] = {
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};
extern char *tzname[2];
static char buf[26];
static void strfmt(char *str, const char *fmt, ...);
/**
*
* size_t strftime(char *str,
* size_t maxs,
* const char *fmt,
* const struct tm *t)
*
* this functions acts much like a sprintf for time/date output.
* given a pointer to an output buffer, a format string and a
* time, it copies the time to the output buffer formatted in
* accordance with the format string. the parameters are used
* as follows:
*
* str is a pointer to the output buffer, there should
* be at least maxs characters available at the address
* pointed to by str.
*
* maxs is the maximum number of characters to be copied
* into the output buffer, included the '\0' terminator
*
* fmt is the format string. a percent sign (%) is used
* to indicate that the following character is a special
* format character. the following are valid format
* characters:
*
* %A full weekday name (Monday)
* %a abbreviated weekday name (Mon)
* %B full month name (January)
* %b abbreviated month name (Jan)
* %c standard date and time representation
* %d day-of-month (01-31)
* %H hour (24 hour clock) (00-23)
* %I hour (12 hour clock) (01-12)
* %j day-of-year (001-366)
* %M minute (00-59)
* %m month (01-12)
* %p local equivalent of AM or PM
* %S second (00-59)
* %U week-of-year, first day sunday (00-53)
* %W week-of-year, first day monday (00-53)
* %w weekday (0-6, sunday is 0)
* %X standard time representation
* %x standard date representation
* %Y year with century
* %y year without century (00-99)
* %Z timezone name
* %% percent sign
*
* the standard date string is equivalent to:
*
* %a %b %d %Y
*
* the standard time string is equivalent to:
*
* %H:%M:%S
*
* the standard date and time string is equivalent to:
*
* %a %b %d %H:%M:%S %Y
*
* strftime returns the number of characters placed in the
* buffer, not including the terminating \0, or zero if more
* than maxs characters were produced.
*
**/
size_t strftime(char *s, size_t maxs, const char *f, const struct tm *t)
{
int w;
char *p, *q, *r;
p = s;
q = s + maxs - 1;
while ((*f != '\0'))
{
if (*f++ == '%')
{
r = buf;
switch (*f++)
{
case '%' :
r = "%";
break;
case 'a' :
r = aday[t->tm_wday];
break;
case 'A' :
r = day[t->tm_wday];
break;
case 'b' :
r = amonth[t->tm_mon];
break;
case 'B' :
r = month[t->tm_mon];
break;
case 'c' :
strfmt(r, "%0 %0 %2 %2:%2:%2 %4",
aday[t->tm_wday], amonth[t->tm_mon],
t->tm_mday,t->tm_hour, t->tm_min,
t->tm_sec, t->tm_year+1900);
break;
case 'd' :
strfmt(r,"%2",t->tm_mday);
break;
case 'H' :
strfmt(r,"%2",t->tm_hour);
break;
case 'I' :
strfmt(r,"%2",(t->tm_hour%12)?t->tm_hour%12:12);
break;
case 'j' :
strfmt(r,"%3",t->tm_yday+1);
break;
case 'm' :
strfmt(r,"%2",t->tm_mon+1);
break;
case 'M' :
strfmt(r,"%2",t->tm_min);
break;
case 'p' :
r = (t->tm_hour>11)?"PM":"AM";
break;
case 'S' :
strfmt(r,"%2",t->tm_sec);
break;
case 'U' :
w = t->tm_yday/7;
if (t->tm_yday%7 > t->tm_wday)
w++;
strfmt(r, "%2", w);
break;
case 'W' :
w = t->tm_yday/7;
if (t->tm_yday%7 > (t->tm_wday+6)%7)
w++;
strfmt(r, "%2", w);
break;
case 'w' :
strfmt(r,"%1",t->tm_wday);
break;
case 'x' :
strfmt(r, "%3s %3s %2 %4", aday[t->tm_wday],
amonth[t->tm_mon], t->tm_mday, t->tm_year+1900);
break;
case 'X' :
strfmt(r, "%2:%2:%2", t->tm_hour,
t->tm_min, t->tm_sec);
break;
case 'y' :
strfmt(r,"%2",t->tm_year%100);
break;
case 'Y' :
strfmt(r,"%4",t->tm_year+1900);
break;
case 'Z' :
r = (t->tm_isdst && tzname[1][0])?tzname[1]:tzname[0];
break;
default:
buf[0] = '%'; /* reconstruct the format */
buf[1] = f[-1];
buf[2] = '\0';
if (buf[1] == 0)
f--; /* back up if at end of string */
}
while (*r)
{
if (p == q)
{
*q = '\0';
return 0;
}
*p++ = *r++;
}
}
else
{
if (p == q)
{
*q = '\0';
return 0;
}
*p++ = f[-1];
}
}
*p = '\0';
return p - s;
}
/*
* stdarg.h
*
typedef void *va_list;
#define va_start(vp,v) (vp=((char*)&v)+sizeo