5.9. Summary

You have been introduced to arrays, pointers and the storage allocater. The last of the topics will prove to be more useful in the next chapter, but the other two are are central to the language.

You cannot use C properly without understanding the use of pointers. Arrays are simple and unsurprising, except for the fact that when it's used in an expression, an array name usually converts into a pointer to its first element; that often takes time to sink in.

The C approach to support for strings often causes raised eyebrows. The null-terminated array of character model is both powerful and flexible. The fact that string manipulation is not built in to the language at first glance seems to rule C out of serious contention for character-oriented work, yet that is exactly where the language scores well compared with the alternatives, at least when speed is important. All the same, it's hard work for the programmer.

Pointer arithmetic is easy and extremely convenient. It's harder for ex-assembler programmers to learn, because of the tendency to try to translate it into what they ‘know’ the machine is doing. However, much harder for people with very low-level experience is the idea of the non-equivalence of pointers of different types. Try hard to throw away the idea that pointers contain addresses (in the hardware sense) and it will repay the effort.

The facility to obtain arbitrary pieces of storage using malloc and the associated stuff is extremely important. You might wish to defer it for a while, but don't leave it for too long. An obvious feature of C programs written by inexperienced users is their dependence on fixed size arrays. Malloc gives you considerably more flexibility and is worth the effort to learn about.

The examples of the use of sizeof should help to eliminate a few common misconceptions about what it does. You may not use it all that often, but when you do need it, there's no substitute.