C++ 获取当前日期精确到毫秒的几种方法

 以下几种方式都是来自网上搜集资料的汇总，对于老的方式，容易出现问题，比如：利用 ftime 函数的， ndk 下，就不通用了，编译不过（函数被弃用），下面的方式都是比较通用的做法，希望对大家有帮助。

方法一：

1#include <stdio.h>
2#include <string.h>
3#include <sys/time.h>
4#include <iostream>
5#include <iomanip>
6#include <ctime>
7#include <chrono>
8/*
9取当前时间，精确到微秒；
10*/
11int main(int argc, char *argv[])
12{
13    auto now = std::chrono::system_clock::now();
14    //通过不同精度获取相差的毫秒数
15    uint64_t dis_millseconds = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()).count()
16        - std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch()).count() * 1000;
17    time_t tt = std::chrono::system_clock::to_time_t(now);
18    auto time_tm = localtime(&tt);
19    char strTime[25] = { 0 };
20    sprintf(strTime, "%d-%02d-%02d %02d:%02d:%02d %03d", time_tm->tm_year + 1900,
21        time_tm->tm_mon + 1, time_tm->tm_mday, time_tm->tm_hour,
22        time_tm->tm_min, time_tm->tm_sec, (int)dis_millseconds);
23    std::cout << strTime << std::endl;
24    return 1;
25}

方法二

1#include <ctime>
2#include <string>
3#include <chrono>
4#include <sstream>
5#include <iomanip>
6#include <iostream>
7
8// use strftime to format time_t into a "date time"
9std::string date_time(std::time_t posix)
10{
11    char buf[20]; // big enough for 2015-07-08 10:06:51\0
12    std::tm tp = *std::localtime(&posix);
13    return {buf, std::strftime(buf, sizeof(buf), "%F %T", &tp)};
14}
15
16std::string stamp()
17{
18    using namespace std;
19    using namespace std::chrono;
20
21    // get absolute wall time
22    auto now = system_clock::now();
23
24    // find the number of milliseconds
25    auto ms = duration_cast<milliseconds>(now.time_since_epoch()) % 1000;
26
27    // build output string
28    std::ostringstream oss;
29    oss.fill('0');
30
31    // convert absolute time to time_t seconds
32    // and convert to "date time"
33    oss << date_time(system_clock::to_time_t(now));
34    oss << '.' << setw(3) << ms.count();
35
36    return oss.str();
37}
38
39int main()
40{
41    std::cout << stamp() << '\n';
42}

方法三 （ 微秒 ）

1std::string stamp()
2{
3    using namespace std;
4    using namespace std::chrono;
5
6    auto now = system_clock::now();
7
8    // use microseconds % 1000000 now
9    auto us = duration_cast<microseconds>(now.time_since_epoch()) % 1000000;
10
11    std::ostringstream oss;
12    oss.fill('0');
13
14    oss << date_time(system_clock::to_time_t(now));
15    oss << '.' << setw(6) << us.count();
16
17    return oss.str();
18}

good luck