Category : C++ Source Code
Archive : VCCRT1.ZIP
Filename : STRFTIME.C
Output of file : STRFTIME.C contained in archive : VCCRT1.ZIP
*strftime.c - String Format Time
*
* Copyright (c) 1988-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
*
*******************************************************************************/
#include
#include
#include
/* Prototypes for local routines */
static void near pascal _store_str (char *in, char **out, size_t *count);
static void near pascal _store_num (int num, int digits, char **out, size_t *count);
static void near pascal _store_time (const struct tm *tmptr, char **out, size_t *count);
static void near pascal _store_date (const struct tm *tmptr, char **out, size_t *count);
/* Length of the date and time representation strings. [In the future,
these values may appear in the locale-specific structure.] */
#define _DATE_LENGTH 8 /* mm-dd-yy (null not included) */
#define _TIME_LENGTH 8 /* hh:mm:ss (null not included) */
/* Define the max length for each string type including space for a null. */
#define _MAX_WDAY_ABBR 4
#define _MAX_WDAY 10
#define _MAX_MONTH_ABBR 4
#define _MAX_MONTH 10
#define _MAX_AMPM 3
/* LC_TIME localization structure */
struct _lc_time_data {
char wday_abbr[7][_MAX_WDAY_ABBR];
char wday[7][_MAX_WDAY];
char month_abbr[12][_MAX_MONTH_ABBR];
char month[12][_MAX_MONTH];
char ampm[2][_MAX_AMPM];
};
/* LC_TIME data for local "C" */
struct _lc_time_data _lc_time_c = {
{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"},
{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
"Friday", "Saturday", },
{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
"Sep", "Oct", "Nov", "Dec"},
{"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October",
"November", "December"},
{"AM", "PM"}
};
/* Pointer to the current LC_TIME data structure. */
struct _lc_time_data *_lc_time_curr = &_lc_time_c;
/***
*size_t strftime(string, maxsize, format, timeptr) - Format a time string
*
*Purpose:
* Place characters into the user's output buffer expanding time
* format directives as described in the user's control string.
* Use the supplied 'tm' structure for time data when expanding
* the format directives.
* [ANSI]
*
*Entry:
* char *string = pointer to output string
* size_t maxsize = max length of string
* const char *format = format control string
* const struct tm *timeptr = pointer to tb data structure
*
*Exit:
* !0 = If the total number of resulting characters including the
* terminating null is not more than 'maxsize', then return the
* number of chars placed in the 'string' array (not including the
* null terminator).
*
* 0 = Otherwise, return 0 and the contents of the string are
* indeterminate.
*
*Exceptions:
*
*******************************************************************************/
size_t strftime(string, maxsize, format, timeptr)
char *string;
size_t maxsize;
const char *format;
const struct tm *timeptr;
{
struct _lc_time_data *lc_time; /* lc_time data pointer */
size_t left; /* space left in output string */
unsigned temp; /* temps */
int wdaytemp;
/* Copy maxsize into temp. */
left = maxsize;
/* Get a copy of the current _lc_time_data pointer. This
should prevent the necessity of locking/unlocking in mthread
code (if we can guarrentee that the various _lc_time data
structures are always in the same segment). */
lc_time = _lc_time_curr;
/* Copy the input string to the output string expanding the format
designations appropriately. Stop copying when one of the following
is true: (1) we hit a null char in the input stream, or (2) there's
no room left in the output stream. */
while (left > 0)
switch(*format) {
case('\0'):
/* end of format input string */
goto done;
case('%'):
/* Format directive. Take appropriate action based
on format control character. */
format++; /* skip over % char */
switch(*format++) { /* switch on format char */
case('a'): /* abbreviated weekday name */
_store_str(lc_time->wday_abbr[timeptr->tm_wday],
&string, &left);
break;
case('A'): /* full weekday name */
_store_str(lc_time->wday[timeptr->tm_wday],
&string, &left);
break;
case('b'): /* abbreviated month name */
_store_str(lc_time->month_abbr[timeptr->tm_mon],
&string, &left);
break;
case('B'): /* full month name */
_store_str(lc_time->month[timeptr->tm_mon],
&string, &left);
break;
case('c'): /* date and time display */
if ((_DATE_LENGTH+_TIME_LENGTH+1) < left) {
_store_date(timeptr, &string, &left);
*string++=' '; left--;
_store_time(timeptr, &string, &left);
}
else
left=0;
break;
case('d'): /* mday in decimal (01-31) */
_store_num(timeptr->tm_mday, 2, &string, &left);
break;
case('H'): /* 24-hour decimal (00-23) */
_store_num(timeptr->tm_hour, 2, &string, &left);
break;
case('I'): /* 12-hour decimal (01-12) */
if (!(temp = timeptr->tm_hour%12))
temp=12;
_store_num(temp, 2, &string, &left);
break;
case('j'): /* yday in decimal (001-366) */
_store_num(timeptr->tm_yday+1, 3, &string, &left);
break;
case('m'): /* month in decimal (01-12) */
_store_num(timeptr->tm_mon+1, 2, &string, &left);
break;
case('M'): /* minute in decimal (00-59) */
_store_num(timeptr->tm_min, 2, &string, &left);
break;
case('p'): /* AM/PM designation */
if (timeptr->tm_hour <= 11)
_store_str(lc_time->ampm[0], &string, &left);
else
_store_str(lc_time->ampm[1], &string, &left);
break;
case('S'): /* secs in decimal (00-59) */
_store_num(timeptr->tm_sec, 2, &string, &left);
break;
case('U'): /* sunday week number (00-53) */
wdaytemp = timeptr->tm_wday;
goto weeknum; /* join common code */
case('w'): /* week day in decimal (0-6) */
_store_num(timeptr->tm_wday, 1, &string, &left);
break;
case('W'): /* monday week number (00-53) */
if (timeptr->tm_wday == 0) /* monday based */
wdaytemp = 6;
else
wdaytemp = timeptr->tm_wday-1;
weeknum:
if (timeptr->tm_yday < wdaytemp)
temp=0;
else {
temp = timeptr->tm_yday/7;
if ((timeptr->tm_yday%7) >= wdaytemp)
temp++;
}
_store_num(temp, 2, &string, &left);
break;
case('x'): /* date display */
_store_date(timeptr, &string, &left);
break;
case('X'): /* time display */
_store_time(timeptr, &string, &left);
break;
case('y'): /* year w/o century (00-99) */
temp = timeptr->tm_year%100;
_store_num(temp, 2, &string, &left);
break;
case('Y'): /* year w/ century */
temp = (((timeptr->tm_year/100)+19)*100) +
(timeptr->tm_year%100);
_store_num(temp, 4, &string, &left);
break;
case('z'): /* time zone name, if any */
case('Z'): /* ANSI specifies 'Z', also support 'z' */
__tzset(); /* set up tz info */
_store_str(_tzname[((timeptr->tm_isdst)?1:0)],
&string, &left);
break;
case('%'): /* percent sign */
*string++ = '%';
left--;
break;
default: /* unknown format directive */
/* ignore the directive and continue */
/* [ANSI: Behavior is undefined.] */
break;
} /* end % switch */
break;
default:
/* store character, bump pointers, dec the char count */
*string++ = *format++;
left--;
break;
}
/* All done. See if we terminated because we hit a null char or because
we ran out of space */
done:
if (left > 0) {
/* Store a terminating null char and return the number of chars
we stored in the output string. */
*string = '\0';
return(maxsize-left);
}
else
return(0);
}
/***
*_store_str() - Copy a time string
*
*Purpose:
* Copy the supplied time string into the output string until
* (1) we hit a null in the time string, or (2) the given count
* goes to 0.
*
* *** For internal use with strftime() only ***
*
*Entry:
* char *in = pointer to null terminated time string
* char **out = address of pointer to output string
* size_t *count = address of char count (space in output area)
*
*Exit:
* none
*Exceptions:
*
*******************************************************************************/
static void near pascal _store_str (in, out, count)
char *in;
char **out;
size_t *count;
{
while ((*count > 0) && (*in != '\0')) {
*(*out)++ = *in++;
(*count)--;
}
}
/***
*_store_num() - Convert a number to ascii and copy it
*
*Purpose:
* Convert the supplied number to decimal and store
* in the output buffer. Update both the count and
* buffer pointers.
*
* *** For internal use with strftime() only ***
*
*Entry:
* int num = integer value
* int digits = # of ascii digits to put into string
* char **out = address of pointer to output string
* size_t *count = address of char count (space in output area)
*
*Exit:
* none
*Exceptions:
*
*******************************************************************************/
static void near pascal _store_num (num, digits, out, count)
int num;
int digits;
char **out;
size_t *count;
{
int temp=0;
if ((size_t)digits < *count) {
for (digits--; (digits+1); digits--) {
(*out)[digits] = (char)('0' + num % 10);
num /= 10;
temp++;
}
*out += temp;
*count -= temp;
}
else
*count = 0;
}
/***
*_store_time() - Store time in appropriate format
*
*Purpose:
* Format the time in the current locale's format
* and store it in the supplied buffer.
*
* [*** Currently, this routine assumes standard "C"
* locale. When full localization support is introduced,
* this functionality will have to be expanded.]
*
* Standard "C" locale time format:
*
* hh:mm:ss
*
* *** For internal use with strftime() only ***
*
*Entry:
*
* const struct tm *tmptr = pointer to time/date structure
* char **out = address of pointer to output string
* size_t *count = address of char count (space in output area)
*
*Exit:
* none
*Exceptions:
*
*******************************************************************************/
static void near pascal _store_time (tmptr, out, count)
const struct tm *tmptr;
char **out;
size_t *count;
{
if (_TIME_LENGTH < *count) {
_store_num(tmptr->tm_hour, 2, out, count);
*(*out)++ = ':';
_store_num(tmptr->tm_min, 2, out, count);
*(*out)++ = ':';
_store_num(tmptr->tm_sec, 2, out, count);
*count -= 2; /* count the colons */
}
else
*count = 0;
}
/***
*_store_date() - Store date in appropriate format
*
*Purpose:
* Format the date in the current locale's format
* and store it in the supplied buffer.
*
* [*** Currently, this routine assumes standard "C"
* locale. When full localization support is introduced,
* this functionality will have to be expanded.]
*
* Standard "C" locale date format:
*
* mm/dd/yy
*
* *** For internal use with strftime() only ***
*
*Entry:
*
* const struct tm *tmptr = pointer to time/date structure
* char **out = address of pointer to output string
* size_t *count = address of char count (space in output area)
*
*Exit:
* none
*Exceptions:
*
*******************************************************************************/
static void near pascal _store_date (tmptr, out, count)
const struct tm *tmptr;
char **out;
size_t *count;
{
if (_DATE_LENGTH < *count) {
_store_num(tmptr->tm_mon+1, 2, out, count);
*(*out)++ = '/';
_store_num(tmptr->tm_mday, 2, out, count);
*(*out)++ = '/';
_store_num(tmptr->tm_year%100, 2, out, count);
*count -= 2; /* count the backslashes */
}
else
*count = 0;
}
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