#include <sys/time.h>
#include "stdio.h"
int main(void)
{
struct timeval tv;
gettimeofday(&tv,NULL);
printf("now tv_sec=%d,tv_usec=%d\n",tv.tv_sec,tv.tv_usec);
}

#include <time.h>
#include "stdio.h"
int main(void)
{
time_t t =time(NULL);
printf("The Calendar Time now is %d\n",t);
}

#include <time.h>
#include "stdio.h"
int main(void)
{
time_t t =time(NULL);
printf("The Calendar Time now is %d\n",t);struct tm * tmt=localtime(&t);
printf("%02d:%02d:%02d ",tmt->tm_hour,tmt->tm_min,tmt->tm_sec);}

4.产生随机数,每次产生时使用系统时间的us作为种子

srand(tv.tv_usec);
int i_num_rand=1+rand()%7;//decide how many devices,1-7

zigbee c

void osal_ConvertUTCTime( UTCTimeStruct *tm, UTCTime secTime )
 @param   secTime - number of seconds since 0 hrs, 0 minutes,
        0 seconds, on the 1st of January 2000 UTC
即

    UTCTime secTime1=426551686;//linux下获取的是1970至今的秒数，osal下获取的是2000至今的秒数，差值是 943977628osal_setClock(secTime1);UTCTime secTime2=osal_getClock();UTCTimeStruct tm;osal_memset(&tm,0,sizeof(UTCTimeStruct));osal_ConvertUTCTime(&tm,secTime2);

附linux下glibc time.h

/* Copyright (C) 1991-2003,2006,2009 Free Software Foundation, Inc.This file is part of the GNU C Library.The GNU C Library is free software; you can redistribute it and/ormodify it under the terms of the GNU Lesser General PublicLicense as published by the Free Software Foundation; eitherversion 2.1 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 WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNULesser General Public License for more details.You should have received a copy of the GNU Lesser General PublicLicense along with the GNU C Library; if not, write to the FreeSoftware Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307 USA.  *//** ISO C99 Standard: 7.23 Date and time    <time.h>*/#ifndef _TIME_H#if (! defined __need_time_t && !defined __need_clock_t && \! defined __need_timespec)
# define _TIME_H    1
# 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 clockticks per second.  */
# include <bits/time.h>/* This is the obsolete POSIX.1-1988 name for the same constant.  */
# if !defined __STRICT_ANSI__ && !defined __USE_XOPEN2K
#  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>__BEGIN_NAMESPACE_STD
/* Returned by `clock'.  */
typedef __clock_t clock_t;
__END_NAMESPACE_STD
#if defined __USE_XOPEN || defined __USE_POSIX || defined __USE_MISC
__USING_NAMESPACE_STD(clock_t)
#endif#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>__BEGIN_NAMESPACE_STD
/* Returned by `time'.  */
typedef __time_t time_t;
__END_NAMESPACE_STD
#if defined __USE_POSIX || defined __USE_MISC || defined __USE_SVID
__USING_NAMESPACE_STD(time_t)
#endif#endif /* time_t not defined and <time.h> or need time_t.  */
#undef  __need_time_t#if !defined __clockid_t_defined && \((defined _TIME_H && defined __USE_POSIX199309) || defined __need_clockid_t)
# define __clockid_t_defined    1# include <bits/types.h>/* Clock ID used in clock and timer functions.  */
typedef __clockid_t clockid_t;#endif /* clockid_t not defined and <time.h> or need clockid_t.  */
#undef  __clockid_time_t#if !defined __timer_t_defined && \((defined _TIME_H && defined __USE_POSIX199309) || defined __need_timer_t)
# define __timer_t_defined  1# include <bits/types.h>/* Timer ID returned by `timer_create'.  */
typedef __timer_t timer_t;#endif /* timer_t not defined and <time.h> or need timer_t.  */
#undef  __need_timer_t#if !defined __timespec_defined &&                \((defined _TIME_H &&                   \(defined __USE_POSIX199309 || defined __USE_MISC)) ||  \defined __need_timespec)
# define __timespec_defined 1# include <bits/types.h> /* This defines __time_t for us.  *//* POSIX.1b structure for a time value.  This is like a `struct timeval' buthas nanoseconds instead of microseconds.  */
struct timespec{__time_t tv_sec;        /* Seconds.  */long int tv_nsec;        /* Nanoseconds.  */};#endif /* timespec not defined and <time.h> or need timespec.  */
#undef  __need_timespec#ifdef   _TIME_H
__BEGIN_NAMESPACE_STD
/* 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_BSDlong int tm_gmtoff;        /* Seconds east of UTC.  */__const char *tm_zone;   /* Timezone abbreviation.  */
#elselong int __tm_gmtoff;      /* Seconds east of UTC.  */__const char *__tm_zone; /* Timezone abbreviation.  */
#endif
};
__END_NAMESPACE_STD
#if defined __USE_XOPEN || defined __USE_POSIX || defined __USE_MISC
__USING_NAMESPACE_STD(tm)
#endif#ifdef __USE_POSIX199309
/* POSIX.1b structure for timer start values and intervals.  */
struct itimerspec{struct timespec it_interval;struct timespec it_value;};/* We can use a simple forward declaration.  */
struct sigevent;#endif  /* POSIX.1b */#ifdef __USE_XOPEN2K
# ifndef __pid_t_defined
typedef __pid_t pid_t;
#  define __pid_t_defined
# endif
#endif__BEGIN_NAMESPACE_STD
/* 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 (void) __THROW;/* Return the current time and put it in *TIMER if TIMER is not NULL.  */
extern time_t time (time_t *__timer) __THROW;/* Return the difference between TIME1 and TIME0.  */
extern double difftime (time_t __time1, time_t __time0)__THROW __attribute__ ((__const__));/* Return the `time_t' representation of TP and normalize TP.  */
extern time_t mktime (struct tm *__tp) __THROW;/* Format TP into S according to FORMAT.Write no more than MAXSIZE characters and return the numberof characters written, or 0 if it would exceed MAXSIZE.  */
extern size_t strftime (char *__restrict __s, size_t __maxsize,__const char *__restrict __format,__const struct tm *__restrict __tp) __THROW;
__END_NAMESPACE_STD# 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 (__const char *__restrict __s,__const char *__restrict __fmt, struct tm *__tp)__THROW;
# endif# ifdef __USE_XOPEN2K8
/* Similar to the two functions above but take the information fromthe provided locale and not the global locale.  */
# include <xlocale.h>extern size_t strftime_l (char *__restrict __s, size_t __maxsize,__const char *__restrict __format,__const struct tm *__restrict __tp,__locale_t __loc) __THROW;
# endif# ifdef __USE_GNU
extern char *strptime_l (__const char *__restrict __s,__const char *__restrict __fmt, struct tm *__tp,__locale_t __loc) __THROW;
# endif__BEGIN_NAMESPACE_STD
/* Return the `struct tm' representation of *TIMERin Universal Coordinated Time (aka Greenwich Mean Time).  */
extern struct tm *gmtime (__const time_t *__timer) __THROW;/* Return the `struct tm' representationof *TIMER in the local timezone.  */
extern struct tm *localtime (__const time_t *__timer) __THROW;
__END_NAMESPACE_STD# 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 (__const time_t *__restrict __timer,struct tm *__restrict __tp) __THROW;/* Return the `struct tm' representation of *TIMER in local time,using *TP to store the result.  */
extern struct tm *localtime_r (__const time_t *__restrict __timer,struct tm *__restrict __tp) __THROW;
# endif /* POSIX or misc */__BEGIN_NAMESPACE_STD
/* 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 (__const struct tm *__tp) __THROW;/* Equivalent to `asctime (localtime (timer))'.  */
extern char *ctime (__const time_t *__timer) __THROW;
__END_NAMESPACE_STD# 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 (__const struct tm *__restrict __tp,char *__restrict __buf) __THROW;/* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'.  */
extern char *ctime_r (__const time_t *__restrict __timer,char *__restrict __buf) __THROW;
# 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 (void) __THROW;
# 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 (__const time_t *__when) __THROW;
# 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 domainlocaltime package.  These are included only for compatibility.  *//* Like `mktime', but for TP represents Universal Time, not local time.  */
extern time_t timegm (struct tm *__tp) __THROW;/* Another name for `mktime'.  */
extern time_t timelocal (struct tm *__tp) __THROW;/* Return the number of days in YEAR.  */
extern int dysize (int __year) __THROW  __attribute__ ((__const__));
# endif# ifdef __USE_POSIX199309
/* Pause execution for a number of nanoseconds.This function is a cancellation point and therefore not marked with__THROW.  */
extern int nanosleep (__const struct timespec *__requested_time,struct timespec *__remaining);/* Get resolution of clock CLOCK_ID.  */
extern int clock_getres (clockid_t __clock_id, struct timespec *__res) __THROW;/* Get current value of clock CLOCK_ID and store it in TP.  */
extern int clock_gettime (clockid_t __clock_id, struct timespec *__tp) __THROW;/* Set clock CLOCK_ID to value TP.  */
extern int clock_settime (clockid_t __clock_id, __const struct timespec *__tp)__THROW;#  ifdef __USE_XOPEN2K
/* High-resolution sleep with the specified clock.This function is a cancellation point and therefore not marked with__THROW.  */
extern int clock_nanosleep (clockid_t __clock_id, int __flags,__const struct timespec *__req,struct timespec *__rem);/* Return clock ID for CPU-time clock.  */
extern int clock_getcpuclockid (pid_t __pid, clockid_t *__clock_id) __THROW;
#  endif/* Create new per-process timer using CLOCK_ID.  */
extern int timer_create (clockid_t __clock_id,struct sigevent *__restrict __evp,timer_t *__restrict __timerid) __THROW;/* Delete timer TIMERID.  */
extern int timer_delete (timer_t __timerid) __THROW;/* Set timer TIMERID to VALUE, returning old value in OVLAUE.  */
extern int timer_settime (timer_t __timerid, int __flags,__const struct itimerspec *__restrict __value,struct itimerspec *__restrict __ovalue) __THROW;/* Get current value of timer TIMERID and store it in VLAUE.  */
extern int timer_gettime (timer_t __timerid, struct itimerspec *__value)__THROW;/* Get expiration overrun for timer TIMERID.  */
extern int timer_getoverrun (timer_t __timerid) __THROW;
# 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 isspecified that can not be represented in a time_t (representingthe 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 valuerepresenting the value.  The templates from the file identified bythe environment variable DATEMSK are used.  In case of an error`getdate_err' is set.This function is a possible cancellation points and therefore notmarked with __THROW.  */
extern struct tm *getdate (__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-safevariant.  The functionality is the same.  The result is returned inthe buffer pointed to by RESBUFP and in case of an error the returnvalue is != 0 with the same values as given above for `getdate_err'.This function is not part of POSIX and therefore no officialcancellation point.  But due to similarity with an POSIX interfaceor due to the implementation it is a cancellation point andtherefore not marked with __THROW.  */
extern int getdate_r (__const char *__restrict __string,struct tm *__restrict __resbufp);
# endif__END_DECLS#endif /* <time.h> included.  */#endif /* <time.h> not already included.  */

附 linux 系统时间 sys/time.h

/* Copyright (C) 1991-1994,1996-2003,2005,2006,2009Free Software Foundation, Inc.This file is part of the GNU C Library.The GNU C Library is free software; you can redistribute it and/ormodify it under the terms of the GNU Lesser General PublicLicense as published by the Free Software Foundation; eitherversion 2.1 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 WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNULesser General Public License for more details.You should have received a copy of the GNU Lesser General PublicLicense along with the GNU C Library; if not, write to the FreeSoftware Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307 USA.  */#ifndef _SYS_TIME_H
#define _SYS_TIME_H 1#include <features.h>#include <bits/types.h>
#define __need_time_t
#include <time.h>
#define __need_timeval
#include <bits/time.h>#include <sys/select.h>#ifndef __suseconds_t_defined
typedef __suseconds_t suseconds_t;
# define __suseconds_t_defined
#endif__BEGIN_DECLS#ifdef __USE_GNU
/* Macros for converting between `struct timeval' and `struct timespec'.  */
# define TIMEVAL_TO_TIMESPEC(tv, ts) {                                   \(ts)->tv_sec = (tv)->tv_sec;                                    \(ts)->tv_nsec = (tv)->tv_usec * 1000;                           \
}
# define TIMESPEC_TO_TIMEVAL(tv, ts) {                                   \(tv)->tv_sec = (ts)->tv_sec;                                    \(tv)->tv_usec = (ts)->tv_nsec / 1000;                           \
}
#endif#ifdef __USE_BSD
/* Structure crudely representing a timezone.This is obsolete and should never be used.  */
struct timezone{int tz_minuteswest;     /* Minutes west of GMT.  */int tz_dsttime;      /* Nonzero if DST is ever in effect.  */};typedef struct timezone *__restrict __timezone_ptr_t;
#else
typedef void *__restrict __timezone_ptr_t;
#endif/* Get the current time of day and timezone information,putting it into *TV and *TZ.  If TZ is NULL, *TZ is not filled.Returns 0 on success, -1 on errors.NOTE: This form of timezone information is obsolete.Use the functions and variables declared in <time.h> instead.  */
extern int gettimeofday (struct timeval *__restrict __tv,__timezone_ptr_t __tz) __THROW __nonnull ((1));#ifdef __USE_BSD
/* Set the current time of day and timezone information.This call is restricted to the super-user.  */
extern int settimeofday (__const struct timeval *__tv,__const struct timezone *__tz)__THROW __nonnull ((1));/* Adjust the current time of day by the amount in DELTA.If OLDDELTA is not NULL, it is filled in with the amountof time adjustment remaining to be done from the last `adjtime' call.This call is restricted to the super-user.  */
extern int adjtime (__const struct timeval *__delta,struct timeval *__olddelta) __THROW;
#endif/* Values for the first argument to `getitimer' and `setitimer'.  */
enum __itimer_which{/* Timers run in real time.  */ITIMER_REAL = 0,
#define ITIMER_REAL ITIMER_REAL/* Timers run only when the process is executing.  */ITIMER_VIRTUAL = 1,
#define ITIMER_VIRTUAL ITIMER_VIRTUAL/* Timers run when the process is executing and whenthe system is executing on behalf of the process.  */ITIMER_PROF = 2
#define ITIMER_PROF ITIMER_PROF};/* Type of the second argument to `getitimer' andthe second and third arguments `setitimer'.  */
struct itimerval{/* Value to put into `it_value' when the timer expires.  */struct timeval it_interval;/* Time to the next timer expiration.  */struct timeval it_value;};#if defined __USE_GNU && !defined __cplusplus
/* Use the nicer parameter type only in GNU mode and not for C++ since thestrict C++ rules prevent the automatic promotion.  */
typedef enum __itimer_which __itimer_which_t;
#else
typedef int __itimer_which_t;
#endif/* Set *VALUE to the current setting of timer WHICH.Return 0 on success, -1 on errors.  */
extern int getitimer (__itimer_which_t __which,struct itimerval *__value) __THROW;/* Set the timer WHICH to *NEW.  If OLD is not NULL,set *OLD to the old value of timer WHICH.Returns 0 on success, -1 on errors.  */
extern int setitimer (__itimer_which_t __which,__const struct itimerval *__restrict __new,struct itimerval *__restrict __old) __THROW;/* Change the access time of FILE to TVP[0] and the modification time ofFILE to TVP[1].  If TVP is a null pointer, use the current time instead.Returns 0 on success, -1 on errors.  */
extern int utimes (__const char *__file, __const struct timeval __tvp[2])__THROW __nonnull ((1));#ifdef __USE_BSD
/* Same as `utimes', but does not follow symbolic links.  */
extern int lutimes (__const char *__file, __const struct timeval __tvp[2])__THROW __nonnull ((1));/* Same as `utimes', but takes an open file descriptor instead of a name.  */
extern int futimes (int __fd, __const struct timeval __tvp[2]) __THROW;
#endif#ifdef __USE_GNU
/* Change the access time of FILE relative to FD to TVP[0] and themodification time of FILE to TVP[1].  If TVP is a null pointer, usethe current time instead.  Returns 0 on success, -1 on errors.  */
extern int futimesat (int __fd, __const char *__file,__const struct timeval __tvp[2]) __THROW;
#endif#ifdef __USE_BSD
/* Convenience macros for operations on timevals.NOTE: `timercmp' does not work for >= or <=.  */
# define timerisset(tvp)    ((tvp)->tv_sec || (tvp)->tv_usec)
# define timerclear(tvp)    ((tvp)->tv_sec = (tvp)->tv_usec = 0)
# define timercmp(a, b, CMP)                              \(((a)->tv_sec == (b)->tv_sec) ?                        \((a)->tv_usec CMP (b)->tv_usec) :                        \((a)->tv_sec CMP (b)->tv_sec))
# define timeradd(a, b, result)                           \do {                                       \(result)->tv_sec = (a)->tv_sec + (b)->tv_sec;               \(result)->tv_usec = (a)->tv_usec + (b)->tv_usec;                \if ((result)->tv_usec >= 1000000)                       \{                                          \++(result)->tv_sec;                           \(result)->tv_usec -= 1000000;                          \}                                          \} while (0)
# define timersub(a, b, result)                           \do {                                       \(result)->tv_sec = (a)->tv_sec - (b)->tv_sec;                \(result)->tv_usec = (a)->tv_usec - (b)->tv_usec;                 \if ((result)->tv_usec < 0) {                         \--(result)->tv_sec;                             \(result)->tv_usec += 1000000;                         \}                                          \} while (0)
#endif  /* BSD */__END_DECLS#endif /* sys/time.h */