C Primer Plus, Fourth Edition

Pointers: A First Look

Pointers? What are they? Basically, a pointer is a variable (or, more generally, a data object) whose value is an address. Just as a char variable has a character as a value and an int variable has an integer as a value, the pointer variable has an address as a value. Pointers have many uses in C; in this chapter, we'll see how and why they are used as function parameters.

If you give a particular pointer variable the name ptr, you can have statements like the following:

ptr = &pooh;  /* assigns pooh's address to ptr */

We say that ptr “points to” pooh. The difference between ptr and &pooh is that ptr is a variable, and &pooh is a constant. If you want, you can make ptr point elsewhere:

 ptr = &bah; /* make ptr point to ...