1、time_t 类型：长整型，一般用来表示从1970-01-01 00:00:00时以来的秒数，精确度：秒；由函数time()获取；
该类型定义在头文件 /usr/include/sys/time.h 中：
#define _TIME_T
typedef long time_t
#endif
函数定义：time_t time(time_t* lpt)；
如：time_t time = time(NULL)；
2、struct timeb 结构：它有两个主要成员，一个是秒，另一个是毫秒；精确度：毫秒(10E-3秒)；
由函数ftime()获取struct timeb结构的时间；其定义如下：
struct timeb
{
time_t time
unsigned short millitm
short timezone
short dstflag
}
#include <sys/timeb.h>
int ftime(struct timeb* tp)
调用成功返回0；调用失败返回-1；
3、struct timeval 结构，它有两个成员；一个是秒，另一个表示微秒，精确度：微秒(10E-6)；
由函数gettime0fday()获取；
struct timeval结构定义为：
struct timeval
{
long tv_sec；
long tv_usec；
}
读取struct timeval结构数据的函数说明：
#include <sys/time.h>
int gettimeofday(struct timeval* tv，struct timezone* tz)；
该函数会提取系统当前时间，并把时间分为秒和微秒两部分填充到结构struct timeval中；同时把当地的时区信
息填充到结构struct timezone中；
返回值：成功则返回0，失败返回－1，错误代码存于errno。附加说明EFAULT指针tv和tz所指的内存空间超出存
取权限。
struct timezone结构的定义为：
struct timezone
{
int tz_minuteswest；
int tz_dsttime；
}
上述两个结构都定义在/usr/include/sys/time.h。tz_dsttime 所代表的状态如下
DST_NONE
DST_USA
DST_AUST
DST_WET
DST_MET
DST_EET
DST_CAN
DST_GB
DST_RUM
DST_TUR
DST_AUSTALT
4、struct timespec 结构：它是POSIX.4标准定义的一个时间结构，精确度：纳秒(10E-9秒)；
由函数gethrestime()或gethrestime_lasttick()获取当前系统struct timespec结构的时间；其定义如下：
struct timespec
{
time_ttv_sec
long tv_nsec
}
typedef struct timespec timespec_t；
该结构定义在头头文件 /usr/include/sys/time_impl.h 中；
extern void gethrestime(timespec_t*)
extern void gethrestime_lasttick(timespec_t*)
5、clock_t 类型：由函数clock()获取；
#include <time.h>
clock_t clock(void)
该函数以微秒的方式返回CPU的时间
类型 clock_t 定义在头文件/usr/include/sys/types.h中：
#ifndef _CLOCK_T
#define _CLOCK_T
typedeflong clock_t
#endif
6、struct tm 结构：由函数gmtime()解析time_t得到
struct tm*gmtime(const time_t*timep)
函数说明：gmtime()将参数timep 所指的time_t 结构中的信息转换成真实世界所使用的时间日期表示方法，然后
将结果由结构tm返回。
结构tm的定义为
struct tm
{
int tm_sec
int tm_min
int tm_hour
int tm_mday
int tm_mon
int tm_year
int tm_wday
int tm_yday
int tm_isdst
}
int tm_sec 代表目前秒数，正常范围为0-59，但允许至61秒
int tm_min 代表目前分数，范围0-59
int tm_hour 从午夜算起的时数，范围为0-23
int tm_mday 目前月份的日数，范围01-31
int tm_mon 代表目前月份，从一月算起，范围从0-11
int tm_year 从1900 年算起至今的年数
int tm_wday 一星期的日数，从星期一算起，范围为0-6
int tm_yday 从今年1月1日算起至今的天数，范围为0-365
int tm_isdst 日光节约时间的旗标
此函数返回的时间日期未经时区转换，而是UTC时间。
返回值：返回结构tm代表目前UTC 时间
7、Unix对时间单位的定义：
#define SEC1// 秒
#define MILLISEC1000 // 毫秒
#define MICROSEC 1000000// 微秒
#define NANOSEC 1000000000 // 纳秒
8、时间格式化函数：
size_t strftime(char *str,size_t max,char *fmt,struct tm *tp) strftime有点像sprintf，其格式由fmt来指定。
%a : 本第几天名称，缩写
%A : 本第几天名称，全称
%b : 月份名称，缩写
%B : 月份名称，全称
%c : 与ctime/asctime格式相同
%d : 本月第几日名称，由零算起
%H : 当天第几个小时，24小时制，由零算起
%I : 当天第几个小时，12小时制，由零算起
%j : 当年第几天，由零算起
%m : 当年第几月，由零算起
%M : 该小时的第几分，由零算起
%p : AM或PM
%S : 该分钟的第几秒，由零算起
%U : 当年第几，由第一个日开始计算
%W : 当年第几，由第一个一开始计算
%w : 当第几日，由零算起
%x : 当地日期
%X : 当地时间
%y : 两位数的年份
%Y : 四位数的年份
%Z : 时区名称的缩写
%% : %符号
char * strptime(char *s,char *fmt,struct tm *tp) 如同scanf一样，解译字串成为tm格式
%h : 与%b及%B同
%c : 读取%x及%X格式
%C : 读取%C格式
%e : 与%d同
%D : 读取%m/%d/%y格式
%k : 与%H同
%l : 与%I同
%r : 读取"%I:%M:%S %p"格式
%R : 读取"%H:%M"格式
%T : 读取"%H:%M:%S"格式
%y : 读取两位数年份
%Y : 读取四位数年份
希望可以帮到你，谢谢！
c语言时间函数：1、获得日历时间函数：
可以通过time()函数来获得日历时间（Calendar Time），其原型为：time_t time(time_t * timer)
如果已经声明了参数timer，可以从参数timer返回现在的日历时间，同时也可以通过返回值返回现在的日历时间，即从一个时间点（例如：1970年1月1日0时0分0秒）到现在此时的秒数。如果参数为空（NUL），函数将只通过返回值返回现在的日历时间，比汪搭如下面这个例子用来塌余显示当前的日历时间：
2、获得日期和时间函数：
这里说的日期和时间就是平时所说的年、月、日、时、分、秒等信息。从第2节我们已经知道这些信息都保存在一个名为tm的结构体中，那么如何将一个日历时间保存为一个tm结构的对象呢？
其中可以使用的函数是gmtime()和localtime()，这两个函数的原型为：
struct tm * gmtime(const time_t *timer)
struct tm * localtime(const time_t * timer)
其中gmtime()函数是将日历时间转化为世界标准时间（即格林尼困衫拿治时间），并返回一个tm结构体来保存这个时间，而localtime()函数是将日历时间转化为本地时间。比如现在用gmtime()函数获得的世界标准时间是2005年7月30日7点18分20秒，那么用localtime()函数在中国地区获得的本地时间会比世界标准时间晚8个小时，即2005年7月30日15点18分20秒。
/*This file is part of the GNU C Library.
The GNU C Library is free softwareyou can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundationeither version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTYwithout even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Librarysee the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/*
* ISO C Standard: 4.12 DATE and TIME <time.h>
*/
#ifndef _TIME_H
#if (! defined __need_time_t &&!defined __need_clock_t &&\
! defined __need_timespec)
# define _TIME_H1
# include <features.h>
__BEGIN_DECLS
#endif
#ifdef _TIME_H
/* Get size_t and NULL from <stddef.h>. */
# define __need_size_t
# define __need_NULL
# include <stddef.h>
/* This defines CLOCKS_PER_SEC, which is the number of processor clock
ticks per second. */
# include <bits/time.h>
/* This is the obsolete POSIX.1-1988 name for the same constant. */
# ifdef __USE_POSIX
# ifndef CLK_TCK
# define CLK_TCK CLOCKS_PER_SEC
# endif
# endif
#endif /* <time.h>included. */
#if !defined __clock_t_defined &&(defined _TIME_H || defined __need_clock_t)
# define __clock_t_defined 1
# include <bits/types.h>
/* Returned by `clock'. */
typedef __clock_t clock_t
#endif /* clock_t not defined and <time.h>or need clock_t. */
#undef __need_clock_t
#if !defined __time_t_defined &&(defined _TIME_H || defined __need_time_t)
# define __time_t_defined 1
# include <bits/types.h>
/* Returned by `time'. */
typedef __time_t time_t
#endif /* time_t not defined and <time.h>or need time_t. */
#undef __need_time_t
#if !defined __timespec_defined &&\
((defined _TIME_H &&defined __USE_POSIX199309) || defined __need_timespec)
# define __timespec_defined 1
/* POSIX.4 structure for a time value. This is like a `struct timeval' but
has nanoseconds instead of microseconds. */
struct timespec
{
long int tv_sec /* Seconds. */
long int tv_nsec /* Nanoseconds. */
}
#endif /* timespec not defined and <time.h>or need timespec. */
#undef __need_timespec
#ifdef _TIME_H
/* Used by other time functions. */
struct tm
{
int tm_sec /* Seconds. [0-60] (1 leap second) */
int tm_min /* Minutes. [0-59] */
int tm_hour /* Hours. [0-23] */
int tm_mday /* Day. [1-31] */
int tm_mon /* Month. [0-11] */
int tm_year /* Year - 1900. */
int tm_wday /* Day of week. [0-6] */
int tm_yday /* Days in year.[0-365] */
int tm_isdst/* DST. [-1/0/1]*/
# ifdef __USE_BSD
long int tm_gmtoff /* Seconds east of UTC. */
__const char *tm_zone /* Timezone abbreviation. */
# else
long int __tm_gmtoff/* Seconds east of UTC. */
__const char *__tm_zone /* Timezone abbreviation. */
# endif
}
/* Time used by the program so far (user time + system time).
The result / CLOCKS_PER_SECOND is program time in seconds. */
extern clock_t clock __P ((void))
/* Return the current time and put it in *TIMER if TIMER is not NULL. */
extern time_t time __P ((time_t *__timer))
/* Return the difference between TIME1 and TIME0. */
extern double difftime __P ((time_t __time1, time_t __time0))
__attribute__ ((__const__))
/* Return the `time_t' representation of TP and normalize TP. */
extern time_t mktime __P ((struct tm *__tp))
/* Format TP into S according to FORMAT.
Write no more than MAXSIZE characters and return the number
of characters written, or 0 if it would exceed MAXSIZE. */
extern size_t strftime __P ((char *__restrict __s, size_t __maxsize,
__const char *__restrict __format,
__const struct tm *__restrict __tp))
# ifdef __USE_XOPEN
/* Parse S according to FORMAT and store binary time information in TP.
The return value is a pointer to the first unparsed character in S. */
extern char *strptime __P ((__const char *__s, __const char *__fmt,
struct tm *__tp))
# endif
/* Return the `struct tm' representation of *TIMER
in Universal Coordinated Time (aka Greenwich Mean Time). */
extern struct tm *gmtime __P ((__const time_t *__timer))
/* Return the `struct tm' representation
of *TIMER in the local timezone. */
extern struct tm *localtime __P ((__const time_t *__timer))
# if defined __USE_POSIX || defined __USE_MISC
/* Return the `struct tm' representation of *TIMER in UTC,
using *TP to store the result. */
extern struct tm *__gmtime_r __P ((__const time_t *__restrict __timer,
struct tm *__restrict __tp))
extern struct tm *gmtime_r __P ((__const time_t *__restrict __timer,
struct tm *__restrict __tp))
/* Return the `struct tm' representation of *TIMER in local time,
using *TP to store the result. */
extern struct tm *localtime_r __P ((__const time_t *__restrict __timer,
struct tm *__restrict __tp))
# endif /* POSIX or misc */
/* Return a string of the form "Day Mon dd hh:mm:ss yyyy\n"
that is the representation of TP in this format. */
extern char *asctime __P ((__const struct tm *__tp))
/* Equivalent to `asctime (localtime (timer))'. */
extern char *ctime __P ((__const time_t *__timer))
# if defined __USE_POSIX || defined __USE_MISC
/* Reentrant versions of the above functions. */
/* Return in BUF a string of the form "Day Mon dd hh:mm:ss yyyy\n"
that is the representation of TP in this format. */
extern char *asctime_r __P ((__const struct tm *__restrict __tp,
char *__restrict __buf))
/* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'. */
extern char *ctime_r __P ((__const time_t *__restrict __timer,
char *__restrict __buf))
# endif /* POSIX or misc */
/* Defined in localtime.c. */
extern char *__tzname[2] /* Current timezone names. */
extern int __daylight /* If daylight-saving time is ever in use. */
extern long int __timezone/* Seconds west of UTC. */
# ifdef __USE_POSIX
/* Same as above. */
extern char *tzname[2]
/* Set time conversion information from the TZ environment variable.
If TZ is not defined, a locale-dependent default is used. */
extern void tzset __P ((void))
# endif
# if defined __USE_SVID || defined __USE_XOPEN
extern int daylight
extern long int timezone
# endif
# ifdef __USE_SVID
/* Set the system time to *WHEN.
This call is restricted to the superuser. */
extern int stime __P ((__const time_t *__when))
# endif
/* Nonzero if YEAR is a leap year (every 4 years,
except every 100th isn't, and every 400th is). */
# define __isleap(year) \
((year) % 4 == 0 &&((year) % 100 != 0 || (year) % 400 == 0))
# ifdef __USE_MISC
/* Miscellaneous functions many Unices inherited from the public domain
localtime package. These are included only for compatibility. */
/* Like `mktime', but for TP represents Universal Time, not local time. */
extern time_t timegm __P ((struct tm *__tp))
/* Another name for `mktime'. */
extern time_t timelocal __P ((struct tm *__tp))
/* Return the number of days in YEAR. */
extern int dysize __P ((int __year))
# endif
# ifdef __USE_POSIX199309
/* Pause execution for a number of nanoseconds. */
extern int nanosleep __P ((__const struct timespec *__requested_time,
struct timespec *__remaining))
# endif
# ifdef __USE_XOPEN_EXTENDED
/* Set to one of the following values to indicate an error.
1 the DATEMSK environment variable is null or undefined,
2 the template file cannot be opened for reading,
3 failed to get file status information,
4 the template file is not a regular file,
5 an error is encountered while reading the template file,
6 memory allication failed (not enough memory available),
7 there is no line in the template that matches the input,
8 invalid input specification Example: February 31 or a time is
specified that can not be represented in a time_t (representing
the time in seconds since 00:00:00 UTC, January 1, 1970) */
extern int getdate_err
/* Parse the given string as a date specification and return a value
representing the value. The templates from the file identified by
the environment variable DATEMSK are used. In case of an error
`getdate_err' is set. */
extern struct tm *getdate __P ((__const char *__string))
# endif
# ifdef __USE_GNU
/* Since `getdate' is not reentrant because of the use of `getdate_err'
and the static buffer to return the result in, we provide a thread-safe
variant. The functionality is the same. The result is returned in
the buffer pointed to by RESBUFP and in case of an error the return
value is != 0 with the same values as given above for `getdate_err'. */
extern int getdate_r __P ((__const char *__restrict __string,
struct tm *__restrict __resbufp))
# endif
__END_DECLS
#endif /* <time.h>included. */
#endif /* <time.h>not already included. */
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