Does returned struct of localtime() need to be freed?

Question

struct tm *localtime(const time_t *timep);

I checked man localtime but there's no words on whether it's my duty to clean it after using.

And in fact I have many similar doubts on functions returning a pointer, how do you determine it should be freed or not ?

Answer 1

This information should be in the man page - my localtime man page says:

The return value points to a statically allocated struct...

Statically allocated objects should not be passed to free(), so this is your answer - no, you should not free the return value of localtime().

The only way to tell in the general case is to consult the documentation or implementation of the function in question.