gettimeofday(struct timeval tv, struct timezone tz)函数

最新推荐文章于 2025-08-07 14:57:48 发布

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本文介绍了一个用于获取当前精确时间（Unix时间）的C语言函数gettimeofday。该函数使用timeval和timezone结构体来分别返回秒数和微秒数，以及进行时区调整。通过示例代码展示了如何调用此函数并打印出当前的时间。

gettimeofday(struct timeval *tv, struct timezone *tz)函数

功能：获取当前精确时间（Unix时间）

其中:

timeval为时间

truct timeval{
long tv_sec; // 秒数
long tv_usec; // 微秒数
}

timezone为时区

#include<stdio.h>
#include<sys/time.h>
int main(){ 
struct timeval tv;
gettimeofday(&tv,NULL);
printf("%d,%d\n",tv.tv_sec,tv.tv_usec);
return 0;
}

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一、struct timespec 定义： #ifndef _TIMESPEC #define _TIMESPEC typedef long time_t; struct timespec { time_t tv_sec; // seconds long tv_nsec; // and nanoseconds }; #endif struct timespec有两个成员，一个是秒，一个是纳秒, 所以最高精确度是纳秒。一般由函数int clock_gettime(c..

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gettimeofday 取得目前的时间例子

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在C++中的核心应用是性能测量、时间戳生成和网络超时控制。，它更轻量，特别适合性能测量和网络编程。，但在需要微秒精度或系统集成的场景下，在C++中的主要优势是。

精选资源

C语言中settimeofday函数和gettimeofday函数的使用

01-01

int settimeofday(const struct timeval *tv, const struct timezone *tz); 函数说明：settimeofday()会把目前时间设成由tv 所指的结构信息，当地时区信息则设成tz 所指的结构。详细的说明请参考gettimeofday()。 ...

int gettimeofday(struct timeval *tv, struct timezone *tz) { FILETIME ft; unsigned __int64 tmpres = 0; static int tzflag; if (NULL != tv) { GetSystemTimeAsFileTime(&ft); tmpres |= ft.dwHighDateTime; tmpres <<= 32; tmpres |= ft.dwLowDateTime; /*converting file time to unix epoch*/ tmpres /= 10; /*convert into microseconds*/ tmpres -= DELTA_EPOCH_IN_MICROSECS; tv->tv_sec = (long)(tmpres / 1000000UL); tv->tv_usec = (long)(tmpres % 1000000UL); } if (NULL != tz) { if (!tzflag) { _tzset(); tzflag++; } tz->tz_minuteswest = _timezone / 60; tz->tz_dsttime = _daylight; } return 0; }

最新发布

09-04

int gettimeofday(struct timeval *tv, struct timezone *tz) { FILETIME ft; unsigned __int64 tmpres = 0; static int tzflag; ``` - `FILETIME`：Windows 中表示文件时间的结构体，精度为 100 纳秒。 - `...

struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ }; struct timezone { int tz_minuteswest; /* minutes west of Greenwich */ int tz_dsttime; /* type of DST correction */ }; 解释一下这个代码

08-13

struct timezone tz; // 获取当前时间 gettimeofday(&tv, &tz); printf("Seconds: %ld\n", tv.tv_sec); printf("Microseconds: %d\n", tv.tv_usec); printf("Minutes west of UTC: %d\n", tz.tz_minuteswest...

unsigned int g_ls_max_num = LS_PRELOAD_MAX_LS_NUM; int g_ls_time_lsid = LS_TIME_LSID_INIT_VALUE; unsigned int g_ls_time_debug = 0; /* admin和ls同时操作是否用锁隔离开 */ int g_ls_use_sem = 0; offset_info_t *g_ls_time_offset[LS_PRELOAD_MAX_LS_NUM + 1] = {NULL}; static inline int gettimeofday_orig(struct timeval *tv, struct timezone *tz) { return g_pfn_ls_gettimeofday ? g_pfn_ls_gettimeofday(tv, tz) : DRV_ERROR; 16 Line113. g_pfn_ls_gettimeofday is true 17 Line113. Assume return here } static inline int settimeofday_orig(const struct timeval *tv, const struct timezone *tz) { return g_pfn_ls_settimeofday ? g_pfn_ls_settimeofday(tv, tz) : DRV_ERROR; } static inline int adjtimex_orig(struct timex *buf) { return g_pfn_ls_adjtimex ? g_pfn_ls_adjtimex(buf) : DRV_ERROR; } static inline int adjtime_orig(const struct timeval *delta, struct timeval *olddelta) { return g_pfn_ls_adjtime ? g_pfn_ls_adjtime(delta, olddelta) : DRV_ERROR; } static inline int sem_wait_timeout(sem_t *sem, int msec) { int ret; while (msec > 0) { 12 Line132. msec > 0 is true ret = sem_trywait(sem); if (ret != -1) { return LS_TIME_SEM_OK; 13 Line135. Assume return here } if (errno == EAGAIN) { (void)usleep(USEC_IN_MSEC); /* sleep for 1ms */ msec--; } else { return LS_TIME_SEM_ERROR; } } return LS_TIME_SEM_TIMEUP; } } return (int)ret; } unsigned int ls_time_sem_wait_ls(int ls_id) { int ret = DRV_OK; if (g_ls_use_sem == 0) { 8 Line215. g_ls_use_sem == 0 is false return 0; } if (g_ls_time_offset[ls_id] && g_ls_time_offset[ls_id]->init_sem) { 9 Line219. g_ls_time_offset[ls_id] is true 10 Line219. g_ls_time_offset[ls_id] && g_ls_time_offset[ls_id]->init_sem is true ret = sem_wait_timeout(&g_ls_time_offset[ls_id]->ls_sem, MSEC_SEMWAIT); 11 Line220. Function sem_wait_timeout is executed if (ret == LS_TIME_SEM_OK) { return DRV_OK; 14 Line222. Assume return here } else if (ret == LS_TIME_SEM_TIMEUP) { /* 如果超时了，则说明LS之前异常复位，需要主动解锁并再加锁 */ if (sem_post(&g_ls_time_offset[ls_id]->ls_sem) == -1) { /* 一般不会进入此分支 */ ret = errno; DEBUG("sem_post ls%d not success(%d), set init flag to 0.", ls_id, ret); } else { /* 如果post后加锁还有问题，就直接返回 */ return (sem_trywait(&g_ls_time_offset[ls_id]->ls_sem) == 0) ? DRV_OK : DRV_ERROR; } } int settimeofday(const struct timeval *tv, const struct timezone *tz) { int ret; unsigned int ls_id; struct timeval tv_admin_old; offset_info_t *info = NULL; unsigned int sem_waited; (void)memset_s(&tv_admin_old, sizeof(struct timeval), 0, sizeof(struct timeval)); 2 Line626. Function memset_s is executed DEBUG_TRACE("setting ls[%d] time", g_ls_time_lsid); if (g_ls_time_lsid < 0) { 4 Line630. g_ls_time_lsid < 0 is false /* 如果lsid未初始化，使用原来的 */ return settimeofday_orig(tv, tz); } if (g_ls_time_lsid) { 5 Line635. g_ls_time_lsid is true struct timeval tv_ls_old; unsigned int sem_ret; /* ls容器内修改时间 */ info = g_ls_time_offset[g_ls_time_lsid]; /* 获取偏移失败，为提高可靠性，认为不需要偏移并直接返回 */ if (info == NULL) { 6 Line642. info == NULL is false DEBUG("settimeofday get ls%d offset not success.", g_ls_time_lsid); return DRV_OK; } sem_ret = ls_time_sem_wait_ls(g_ls_time_lsid); 7 Line647. Function ls_time_sem_wait_ls is executed ret = gettimeofday_orig(&tv_admin_old, NULL); 15 Line649. Function gettimeofday_orig is executed if (ret) { 18 Line650. ret is false if (sem_ret == 0) { (void)ls_time_sem_post_ls(g_ls_time_lsid); } DEBUG("gettimeofday_orig not success %d.", ret); return ret; } /* 调用ls_time_calc更新下adjtime_delta，如果有的话 */ (void)ls_time_calc(&tv_ls_old, &tv_admin_old, info); info->ls_start = TIME_TV2USEC(*tv); 19 Line660. Dereferencing of "tv" which can be null Dereferencing of "tv" which can be null 告警处理帮助 info->admin_start = TIME_TV2USEC(tv_admin_old); info->offset = info->ls_start - info->admin_start; /* 基于新的admin start设置了偏移，所以admin_start也重新设置一下, 否则需要计算出admin原来偏移的时间 */ ret = ls_time_offset_info_set(g_ls_time_lsid, info); if (sem_ret == 0) { (void)ls_time_sem_post_ls(g_ls_time_lsid); } } else {

05-15

settimeofday函数的原型是int settimeofday(const struct timeval *tv, const struct timezone *tz);。根据man手册，tv参数如果为NULL，表示不设置时间，只设置时区。但实际使用中，tv是否为NULL需要根据具体需求来...

c函数之gettimeofday()函数获取系统时间