Use of open() system call in different ways
	new file:   open_basic.c
	new file:   open_creat.c
	new file:   open_creat_excl.c
	new file:   open_trunc.c
	modified:   04_Linked_Lists/singly_linkelist.c
	thread examples
	new file:   Makefile
	new file:   prime.c
	new file:   thread_create.c
	new file:   thread_create2.c
	Use of deference operator and address of operator with precedence
	new file:   deref.c