How is the result struct of localtime allocated in C?

Question

I was playing with the time.h file in C that helps us with time/day functions.

I came across:

struct tm * _Cdecl localtime(const time_t          


        

Answer 1

The pointer returned by localtime (and some other functions) are actually pointers to statically allocated memory. So you do not need to freed. Furthermore, you should not free it.

http://www.cplusplus.com/reference/clibrary/ctime/localtime/

This structure is statically allocated and shared by the functions gmtime and localtime. Each time either one of these functions is called the content of this structure is overwritten.

EDIT : Appending a few things mentioned in the comments.

A direct result of this shared data-structure is that localtime and similar functions are not thread-safe. The thread-safe solution varies with different platforms. localtime_r for POSIX and localtime_s for MSVC.