linux高精度struct timespec 和 struct timeval

一、struct timespec 定义：

typedef long time_t;
#ifndef _TIMESPEC
#define _TIMESPEC
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(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 );

二、struct timeval 定义：

struct timeval {
time_t tv_sec; // seconds 
long tv_usec; // microseconds 
};
struct timezone{ 
int tz_minuteswest; //miniutes west of Greenwich 
int 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[];
     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[];
     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 ;
 }

---

 #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 *  + ts.tv_nsec / );
 }

 int main()
 {
     struct timespec time1 = { ,  };

     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 ;
 }