Which call newi tem tnewp

be placed upon the programmer; there should be only one function. Pretend there is, and always use memmove.

We could replace the memmove call with the following loop:

2.7 Lists

Next to arrays, lists are the most common data structure in typical programs. Many languages have built-in list types-some, such as Lisp, are based on them-but in C we must build them ourselves. In C++ and Java, lists are implemented by a library, but we still need to know how and when to use it. In this section we're going to discuss lists in C but the lessons apply more broadly.

	head	data 2		NULL data 4
	There are several important differences between arrays and lists. First, arrays have fixed size but a list is always exactly the size it needs to be to hold its contents, plus some per-item storage overhead to hold the pointers. Second, lists can be rearranged by exchanging a few pointers. which is cheaper than the block move necessary in an array. Finally, when items are inserted or deleted the other items aren't moved; if we store pointers to the elements in some other data structure, they won't be invalidated by changes to the list. Nameval tnewp;