1. 结构基本定义
1.1 struct timespec 定义
typedef long time_t;#ifndef _TIMESPEC#define _TIMESPECstruct timespec {time_t tv_sec; // secondslong 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(clockid_t, struct timespec *)获取特定时钟的时间，常用如下4种时钟：
CLOCK_REALTIME 统当前时间，从1970年1.1日算起
CLOCK_MONOTONIC 系统的启动时间，不能被设置
CLOCK_PROCESS_CPUTIME_ID 本进程运行时间
CLOCK_THREAD_CPUTIME_ID 本线程运行时间
struct tm *localtime(const time_t *clock); //线程不安全
struct tm* localtime_r( const time_t* timer, struct tm* result );//线程安全
size_t strftime (char* ptr, size_t maxsize, const char* format,const struct tm* timeptr );
1.2 struct timeval定义
struct timeval {time_t tv_sec; // secondslong tv_usec; // microseconds};struct timezone{int tz_minuteswest; //miniutes west of Greenwichint tz_dsttime; //type of DST correction};
struct timeval有两个成员，一个是秒，一个是微秒, 所以最高精确度是微秒。
一般由函数int gettimeofday(struct timeval *tv, struct timezone *tz)获取系统的时间
#include<stdio.h>#include<time.h>#include<sys/time.h>void nowtime_ns(){printf("---------------------------struct timespec---------------------------------------\n");printf("[time(NULL)]:%ld\n", time(NULL));struct timespec ts;clock_gettime(CLOCK_REALTIME, &ts);printf("clock_gettime : tv_sec=%ld, tv_nsec=%ld\n", ts.tv_sec, ts.tv_nsec);struct tm t;char date_time[64];strftime(date_time, sizeof(date_time), "%Y-%m-%d %H:%M:%S", localtime_r(&ts.tv_sec, &t));printf("clock_gettime : date_time=%s, tv_nsec=%ld\n", date_time, ts.tv_nsec);}void nowtime_us(){printf("---------------------------struct timeval----------------------------------------\n");printf("[time(NULL)] : %ld\n", time(NULL));struct timeval us;gettimeofday(&us,NULL);printf("gettimeofday: tv_sec=%ld, tv_usec=%ld\n", us.tv_sec, us.tv_usec);struct tm t;char date_time[64];strftime(date_time, sizeof(date_time), "%Y-%m-%d %H:%M:%S", localtime_r(&us.tv_sec, &t));printf("gettimeofday: date_time=%s, tv_usec=%ld\n", date_time, us.tv_usec);}int main(int argc, char* argv[]){nowtime_ns();printf("\n");nowtime_us();printf("\n");return 0;}
#include <time.h>// 返回自系统开机以来的毫秒数（tick）unsigned long GetTickCount(){struct timespec ts;clock_gettime(CLOCK_MONOTONIC, &ts);return (ts.tv_sec * 1000 + ts.tv_nsec / 1000000);}int main(){struct timespec time1 = { 0, 0 };clock_gettime(CLOCK_REALTIME, &time1);printf("CLOCK_REALTIME: %d, %d\n", time1.tv_sec, time1.tv_nsec);clock_gettime(CLOCK_MONOTONIC, &time1);printf("CLOCK_MONOTONIC: %d, %d\n", time1.tv_sec, time1.tv_nsec);clock_gettime(CLOCK_MONOTONIC_RAW, &time1);printf("CLOCK_MONOTONIC_RAW: %d, %d\n", time1.tv_sec, time1.tv_nsec);clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &time1);printf("CLOCK_PROCESS_CPUTIME_ID: %d, %d\n", time1.tv_sec,time1.tv_nsec);clock_gettime(CLOCK_THREAD_CPUTIME_ID, &time1);printf("CLOCK_THREAD_CPUTIME_ID: %d, %d\n", time1.tv_sec,time1.tv_nsec);printf("\n%d\n", time(NULL));printf("tick count in ms: %ul\n", GetTickCount());return 0;}
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