Memory: The Stack

Abstract

In the first three chapters, we embark on a practical study of computation. Our goal is to develop and understand a simple but expressive model of computation that will underlie the material in the remainder of this book—and on which you can subsequently draw when learning more advanced programming skills and concepts. In the first chapter, we introduce memory; in the second, procedure. In the third, we combine memory and procedure to study two basic data structures.

Whereas a traditional programming course reserves “pointers” for late in the semester and may not even mention the stack, let alone how function calling works, this chapter covers both—for two reasons. First, manipulating memory is fundamental to practical programming, yet many students, through lack of practice, leave their first programming course unable to do so effectively. By introducing memory manipulation in the first week, students have a full semester to master the topic. Second, the correct usage of call-by-value, call-by-reference, pointers, and arrays is crucial for writing anything but the simplest of programs. Rather than taking an abstract and rule-based perspective, this chapter covers the program stack and the function call protocol, which naturally give rise to these concepts. A mechanistic understanding of computation lays the foundations for the powerful abstraction methodologies that come later.