Converts a broken-down time in a tm structure into a 26-character
    string in the following form:

    Sun Sep 16 01:03:52 1984\n\0

    All fields have a constant width.

    Format

      #include  <time.h>

      char *asctime  (const struct tm *timeptr);

      char *asctime_r  (const struct tm *timeptr, char *buffer);

                                                  (ISO POSIX-1)