“struct tm”中的“tm”代表什么？

Question

Just curious. I've tended to name variables of the type struct tm something like time_bits or similar, since it contains the broken-down calendar time bits. Most of the documentation I've seen refers to this type as 'calendar time', as opposed to 'clock time' or 'epoch seconds' for time_t .

Answer 1

It almost certainly just stands for "time". The ISO standard describes it as a thing:

... which holds the components of a calendar time, called the broken-down time.

Answer 2

If it were named struct time , a lot of people would confuse it with this function:

time_t time(time_t *);

Although in C structure tags don't interfere with variable/function names, having different names for them reduces confusion.