6. Pointer Variables

Pointers are what sets C (and C++) apart from other programming languages. Pointers (officially called pointer variables) are the fifth type of major variable in C that hold the address of some other entity in the C program – most commonly other variables-- but can also be user-defined functions or files. They give a programmer direct access to the computer’s memory – something few if any other languages do (besides C++). Beginners tend to dislike them but seasoned programmers generally love them. Nevertheless, they form the basis of passing by reference and of arrays (see Chap. 7). This chapter explains the concept of pointer variables, including how to define them, declare them and initialize them. Pointer-specific operators such as the address-of and the indirection operators are defined, discussed and used in the hands-on example problems of this chapter. Furthermore, the reader is introduced to pointer math as a prelude to understanding and working with arrays in Chap. 7. Finally, other important topics discussed herein include passing by reference, input/output with pointers, and double pointers.