strptime 函数windows平台上实现
Linux平台下Strptime是格式化一个串到时间格式，听好用的，可惜在windows没有实现，翻阅了C库，直接移植过来，做了简单的测试，还行！但缺少一个函数strcasecmp的实现，将“AM”，“PM”（上下午）
的格式注释掉了，想必大家格式串用上下午的还不多吧。献给大家，希望能用的上。
#include <ctype.h>
#include <string.h>
#include <time.h>
/*
* We do not implement alternate representations. However, we always
* check whether a given modifier is allowed for a certain conversion.
*/
#define ALT_E 0x01
#define ALT_O 0x02
//#define LEGAL_ALT(x) { if (alt_format & ~(x)) return (0); }
#define LEGAL_ALT(x) { ; }
#define TM_YEAR_BASE (1970)
static int conv_num(const char **, int *, int, int);
static int strncasecmp(char *s1, char *s2, size_t n);
static const char *day[7] = {
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
"Friday", "Saturday"
};
static const char *abday[7] = {
"Sun","Mon","Tue","Wed","Thu","Fri","Sat"
};
static const char *mon[12] = {
"January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December"
};
static const char *abmon[12] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
static const char *am_pm[2] = {
"AM", "PM"
};
char *
strptime(const char *buf, const char *fmt, struct tm *tm)
{
char c;
const char *bp;
size_t len = 0;
int alt_format, i, split_year = 0;
bp = buf;
while ((c = *fmt) != '/0') {
/* Clear `alternate' modifier prior to new conversion. */
alt_format = 0;
/* Eat up white-space. */
if (isspace(c)) {
while (isspace(*bp))
bp++;
fmt++;
continue;
}
if ((c = *fmt++) != '%')
goto literal;
again: switch (c = *fmt++) {
case '%': /* "%%" is converted to "%". */
literal:
if (c != *bp++)
return (0);
break;
/*
* "Alternative" modifiers. Just set the appropriate flag
* and start over again.
*/
case 'E': /* "%E?" alternative conversion modifier. */
LEGAL_ALT(0);
alt_format |= ALT_E;
goto again;
case 'O': /* "%O?" alternative conversion modifier. */
LEGAL_ALT(0);
alt_format |= ALT_O;
goto again;
/*
* "Complex" conversion rules, implemented through recursion.
*/
case 'c': /* Date and time, using the locale's format. */
LEGAL_ALT(ALT_E);
if (!(bp = strptime(bp, "%x %X", tm)))
return (0);
break;
case 'D': /* The date as "%m/%d/%y". */
LEGAL_ALT(0);
if (!(bp = strptime(bp, "%m/%d/%y", tm)))
return (0);
break;
case 'R': /* The time as "%H:%M". */
LEGAL_ALT(0);
if (!(bp = strptime(bp, "%H:%M", tm)))
return (0);
break;
case 'r': /* The time in 12-hour clock representation. */
LEGAL_ALT(0);
if (!(bp = strptime(bp, "%I:%M:%S %p", tm)))
return (0);
break;
case 'T': /* The time as "%H:%M:%S". */
LEGAL_ALT(0);
if (!(bp = strptime(bp, "%H:%M:%S", tm)))
return (0);
break;
case 'X': /* The time, using the locale's format. */
LEGAL_ALT(ALT_E);
if (!(bp = strptime(bp, "%H:%M:%S", tm)))
return (0);
break;
case 'x': /* The date, using the locale's format. */
LEGAL_ALT(ALT_E);
if (!(bp = strptime(bp, "%m/%d/%y", tm)))
return (0);
break;
/*
* "Elementary" conversion rules.
*/
case 'A': /* The day of week, using the locale's form. */
case 'a':
LEGAL_ALT(0);
for (i = 0; i < 7; i++) {
/* Full name. */
len = strlen(day[i]);
if (strncasecmp((char *)(day[i]), (char *)bp, len) == 0)
break;
/* Abbreviated name. */
len = strlen(abday[i]);
if (strncasecmp((char *)(abday[i]), (char *)bp, len) == 0)
break;
}
/* Nothing matched. */
if (i == 7)
return (0);
tm->tm_wday = i;
bp += len;
break;
case 'B': /* The month, using the locale's form. */
case 'b':
case 'h':
LEGAL_ALT(0);
for (i = 0; i < 12; i++) {
/* Full name. */
len = strlen(mon[i]);
if (strncasecmp((char *)(mon[i]), (char *)bp, len) == 0)
break;
/* Abbreviated name. */
len = strlen(abmon[i]);
if (strncasecmp((char *)(abmon[i]),(char *) bp, len) == 0)
break;
}
/* Nothing matched. */
if (i == 12)
return (0);
tm->tm_mon = i;
bp += len;
break;
case 'C': /* The century number. */
LEGAL_ALT(ALT_E);
if (!(conv_num(&bp, &i, 0, 99)))
return (0);
if (split_year) {
tm->tm_year = (tm->tm_year % 100) + (i * 100);
} else {
tm->tm_year = i * 100;
split_year = 1;
}
break;
case 'd': /* The day of month. */
case 'e':
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_mday, 1, 31)))
return (0);
break;
case 'k': /* The hour (24-hour clock representation). */
LEGAL_ALT(0);
/* FALLTHROUGH */
case 'H':
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_hour, 0, 23)))
return (0);
break;
case 'l': /* The hour (12-hour clock representation). */
LEGAL_ALT(0);
/* FALLTHROUGH */
case 'I':
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_hour, 1, 12)))
return (0);
if (tm->tm_hour == 12)
tm->tm_hour = 0;
break;
case 'j': /* The day of year. */
LEGAL_ALT(0);
if (!(conv_num(&bp, &i, 1, 366)))
return (0);
tm->tm_yday = i - 1;
break;
case 'M': /* The minute. */
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_min, 0, 59)))
return (0);
break;
case 'm': /* The month. */
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &i, 1, 12)))
return (0);
tm->tm_mon = i - 1;
break;
// case 'p': /* The locale's equivalent of AM/PM. */
// LEGAL_ALT(0);
// /* AM? */
// if (strcasecmp(am_pm[0], bp) == 0) {
// if (tm->tm_hour > 11)
// return (0);
//
// bp += strlen(am_pm[0]);
// break;
// }
// /* PM? */
// else if (strcasecmp(am_pm[1], bp) == 0) {
// if (tm->tm_hour > 11)
// return (0);
//
// tm->tm_hour += 12;
// bp += strlen(am_pm[1]);
// break;
// }
//
// /* Nothing matched. */
// return (0);
case 'S': /* The seconds. */
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_sec, 0, 61)))
return (0);
break;
case 'U': /* The week of year, beginning on sunday. */
case 'W': /* The week of year, beginning on monday. */
LEGAL_ALT(ALT_O);
/*
* XXX This is bogus, as we can not assume any valid
* information present in the tm structure at this
* point to calculate a real value, so just check the
* range for now.
*/
if (!(conv_num(&bp, &i, 0, 53)))
return (0);
break;
case 'w': /* The day of week, beginning on sunday. */
LEGAL_ALT(ALT_O);
if (!(conv_num(&bp, &tm->tm_wday, 0, 6)))
return (0);
break;
case 'Y': /* The year. */
LEGAL_ALT(ALT_E);
if (!(conv_num(&bp, &i, 0, 9999)))
return (0);
tm->tm_year = i - TM_YEAR_BASE;
break;
case 'y': /* The year within 100 years of the epoch. */
LEGAL_ALT(ALT_E | ALT_O);
if (!(conv_num(&bp, &i, 0, 99)))
return (0);
if (split_year) {
tm->tm_year = ((tm->tm_year / 100) * 100) + i;
break;
}
split_year = 1;
if (i <= 68)
tm->tm_year = i + 2000 - TM_YEAR_BASE;
else
tm->tm_year = i + 1900 - TM_YEAR_BASE;
break;
/*
* Miscellaneous conversions.
*/
case 'n': /* Any kind of white-space. */
case 't':
LEGAL_ALT(0);
while (isspace(*bp))
bp++;
break;
default: /* Unknown/unsupported conversion. */
return (0);
}
}
/* LINTED functional specification */
return ((char *)bp);
}
static int
conv_num(const char **buf, int *dest, int llim, int ulim)
{
int result = 0;
/* The limit also determines the number of valid digits. */
int rulim = ulim;
if (**buf < '0' || **buf > '9')
return (0);
do {
result *= 10;
result += *(*buf)++ - '0';
rulim /= 10;
} while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
if (result < llim || result > ulim)
return (0);
*dest = result;
return (1);
}
int strncasecmp(char *s1, char *s2, size_t n)
{
if (n == 0)
return 0;
while (n-- != 0 && tolower(*s1) == tolower(*s2))
{
if (n == 0 || *s1 == '/0' || *s2 == '/0')
break;
s1++;
s2++;
}
return tolower(*(unsigned char *) s1) - tolower(*(unsigned char *) s2);
}
//测试
#include <conio.h>
void main()
{
struct tm newtime;
memset(&newtime,0x00,sizeof(struct tm));
strptime("Tue, 27 Nov 2007 05:35:53","%a, %d %b %Y %H:%M:%S",&newtime);
// strptime("03/10/2004 15:54:19","%d/%m/%Y %H:%M:%S",&newtime);
getch();
}
