Pointers are used everywhere in C, so if you want to use the C language fully you have to have a very good understanding of pointers. They have to become comfortable for you. The goal of this section and the next several that follow is to help you build a complete understanding of pointers and how C uses them. For most people it takes a little time and some practice to become fully comfortable with pointers, but once you master them you are a full-fledged C programmer.
C uses pointers in three different ways:
- C uses pointers to create dynamic data structures -- data structures built up from blocks of memory allocated from the heap at run-time.
- C uses pointers to handle variable parameters passed to functions.
- Pointers in C provide an alternative way to access information stored in arrays. Pointer techniques are especially valuable when you work with strings. There is an intimate link between arrays and pointers in C.
In some cases, C programmers also use pointers because they make the code slightly more efficient. What you will find is that, once you are completely comfortable with pointers, you tend to use them all the time.
We will start this discussion with a basic introduction to pointers and the concepts surrounding pointers, and then move on to the three techniques described above. Especially on this article, you will want to read things twice. The first time through you can learn all the concepts. The second time through you can work on binding the concepts together into an integrated whole in your mind. After you make your way through the material the second time, it will make a lot of sense.