如何将时间转换为纪元时间？

Say I have a specific instant in time where I know the hour, minute, day, second, month, year, etc; how can I convert this epoch time (seconds since 1970)?

假设我有一个特定的时刻，我知道小时，分钟，日，秒，月，年等;我如何转换这个纪元时间（自1970年以来的秒数）？

I can't use Boost, so please don't suggest a Boost solution.

我不能使用Boost，所以请不要建议Boost解决方案。

4 个解决方案

#1

Use the mktime(3) function. For example:

使用mktime（3）函数。例如：

struct tm t = {0};  // Initalize to all 0's
t.tm_year = 112;  // This is year-1900, so 112 = 2012
t.tm_mon = 8;
t.tm_mday = 15;
t.tm_hour = 21;
t.tm_min = 54;
t.tm_sec = 13;
time_t timeSinceEpoch = mktime(&t);
// Result: 1347764053

#2

On Linux, use timegm to avoid having your local time zone subtracted:

在Linux上，使用timegm以避免减去本地时区：

struct tm tm;

// set tm.tm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour, tm.tm_min and tm.tm_sec

tm.tm_year -= 1900; // year start at 1900
tm.tm_mon--;        // months start at january
TIME_STAMP t = timegm(&tm);

#3

mktime() can convert struct tm into seconds-since-Epoch.

mktime（）可以将struct tm转换为second-since-Epoch。

#4

mktime and memset is most portable for me:

mktime和memset对我来说最便携：

struct tm t;
memset(&t, 0, sizeof(tm)); // Initalize to all 0's
time_t timeSinceEpoch = mktime(&t);

#1