Question

我知道这些价值

unsigned char year = 17; // means 2017
unsigned char month = 8;
unsigned char day = 25;
unsigned char hour = 14;
unsigned char minute = 23;
unsigned char second = 54;

如何将这些转换为unix时间戳？我不确定unsigned char是否是表示值的正确方法，我只需要每个值大小为1byte。

Answer 1

Ubervan回答了你的问题

将日期分解为其组成部分，即日，月，年，然后：

struct tm  tm;
time_t rawtime;
time ( &rawtime );
tm = *localtime ( &rawtime );
tm.tm_year = year - 1900;
tm.tm_mon = month - 1;
tm.tm_mday = day;
mktime(&tm);

tm现在可以转换为time_t并进行操作。

您的问题也已解决here。

Answer 2

也许最简单，性能最高的方法是使用Howard Hinnant's free, open-source, header-only datetime library：

#include "date.h"
#include <iostream>

date::sys_seconds
to_sys_time(unsigned char y, unsigned char m, unsigned char d,
            unsigned char h, unsigned char M, unsigned char s)
{
    using namespace date;
    using namespace std::chrono;
    return sys_days{year{y+2000}/m/d} + hours{h} + minutes{M} + seconds{s};
}

int
main()
{
    std::cout << to_sys_time(17, 9, 25, 14, 23, 54).time_since_epoch().count() << '\n';
}

输出：

1503671034

此库扩展了<chrono>库以处理日历计算，并且是even being proposed for standardization。

Answer 3

这就是我如何接受c ++ 11的更多内容。

std::string timepointToString(std::chrono::system_clock::time_point const& t) {
  time_t tt = std::chrono::system_clock::to_time_t(t);
  struct tm tb;
  size_t const len(21);
  char buffer[len];
  TRI_gmtime(tt, &tb);
  ::strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M:%SZ", &tb);
  return std::string(buffer, len - 1);
}

std::chrono::system_clock::time_point stringToTimepoint(std::string const& s) {
  if (!s.empty()) {
    try {
      std::tm tt;
      tt.tm_year = std::stoi(s.substr(0, 4)) - 1900;
      tt.tm_mon = std::stoi(s.substr(5, 2)) - 1;
      tt.tm_mday = std::stoi(s.substr(8, 2));
      tt.tm_hour = std::stoi(s.substr(11, 2));
      tt.tm_min = std::stoi(s.substr(14, 2));
      tt.tm_sec = std::stoi(s.substr(17, 2));
      tt.tm_isdst = 0;
      auto time_c = TRI_timegm(&tt);
      return std::chrono::system_clock::from_time_t(time_c);
    } catch (...) {}
  }
  return std::chrono::time_point<std::chrono::system_clock>();
}

C ++将datetime转换为时间戳

3 个答案: