Difference between C standard library and C POSIX library

Question

I\'m a little confused by \"C standard lib\" and \"C POSIX lib\", because I found that, many header files defined in \"C POSIX lib\" are also part of \"C standard lib\".

Answer 1

POSIX is a superset of the standard C library, and it's important to note that it defers to it. If C and POSIX is ever in conflict, C wins.

Sockets, file descriptors, shared memory etc. are all part of POSIX, but do not exist in the C library.

pthread.h is used for POSIX threads and threads.h is a new header for C11 and is part of the C library. Perhaps pthreads will be deprecated sometime in the future in favor of the C ones, however you probably can't count on C11 to have widespread deployment yet. Therefore if you want portability you should prefer pthreads for now. If portability is not a concern, and you have C11 threads available, you should probably use those.