把一个年、月、日、时、分、秒的时间转换为一个基于1970年1月1日0时0分0秒的秒数；或者把一个基于1970年1月1日0时0分0秒的秒数转换为一个年、月、日、时、分、秒的时间。本源码考虑了闰年因素的影响。在嵌入式开发中，当没有RTC时，这种转换非常有用，可以比较容易地维持一个系统时间。-put a year, month, day and hour, minute and second time for a change based on at 0:00 a.m. on January 1, 1970 0 0 seconds seconds; Or one based at 12:00 a.m. on January 1, 1970 0 0 seconds concurrently converted to a year, month, day and hour- and second time. Consider the source of the impact of a leap year. In embedded development, in the absence of the RTC, such a conversion is very useful, it is easier to maintain a system of time.