在window環境下：
1、精確到毫秒

#include "stdafx.h"
#include <windows.h>
#include <iostream>
 
using namespace std;
 
int main(int argc, _TCHAR* argv[])
{
    DWORD time_start, time_end;
    /* 獲取開始時間 */
    time_start = GetTickCount(); //從操作系統啟動經過的毫秒數
    Sleep(3000);
    time_end = GetTickCount();
    cout << "Time = " << (time_end - time_start) << "ms\n ";
 
    
    return 0;
}

#include <time.h>
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clock_t start,ends;
start=clock();
Sleep(50);
ends=clock();
cout<<ends-start<<endl;

time_t 獲得時間只能精確到秒,clock_t 獲得時間能夠精確到毫秒

2、精確到秒

unsigned long long Utils::GetCurrentTimeMsec()
{
#ifdef _WIN32
    struct timeval tv;
    time_t clock;
    struct tm tm;
    SYSTEMTIME wtm;
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    GetLocalTime(&wtm);
    tm.tm_year = wtm.wYear - 1900;
    tm.tm_mon = wtm.wMonth - 1;
    tm.tm_mday = wtm.wDay;
    tm.tm_hour = wtm.wHour;
    tm.tm_min = wtm.wMinute;
    tm.tm_sec = wtm.wSecond;
    tm.tm_isdst = -1;
    clock = mktime(&tm);
    tv.tv_sec = clock;
    tv.tv_usec = wtm.wMilliseconds * 1000;
    return ((unsigned long long)tv.tv_sec * 1000 + (unsigned long long)tv.tv_usec / 1000);
#else
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return ((unsigned long long)tv.tv_sec * 1000 + (unsigned long long)tv.tv_usec / 1000);
#endif
}

在Linux環境下
1. 精確到毫秒

#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
 
int main(int argc, char *argv[])
{
    struct timeval time;
 
    /* 獲取時間，理論到us */
    gettimeofday(&time, NULL);
    printf("s: %ld, ms: %ld\n", time.tv_sec, (time.tv_sec*1000 + time.tv_usec/1000));
 
    sleep(3);  //延時
 
    /* 重新獲取 */
    gettimeofday(&time, NULL);
    printf("s: %ld, ms: %ld\n", time.tv_sec, (time.tv_sec*1000 + time.tv_usec/1000));
 
 
    exit(0);
}

2. 精確到秒

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
 
int main(int argc, char *argv[])
{
 
    time_t t;
    struct tm *tmp;
    char buf2[64];
 
    /* 獲取時間 */
    time(&t);
    tmp = localtime(&t);
 
    /* 轉化時間 */
    if (strftime(buf2, 64, "time and data: %r, %a %b %d, %Y", tmp) == 0) {
        printf("buffer length 64 is too small\n");
    } else {
        printf("%s\n", buf2);
    }
 
    exit(0);
}

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