So far, our programs have had a rather limited interaction with the user or rest of the system, printing some results to standard output (typically to the terminal). Now that we have learned about topics such as strings and arrays, we are ready to learn how to write a program that takes input from the user, takes arguments on the command line, accesses files, and does many other things we typically think of real programs as doing.

So far, most of the memory we have used has been located on the stack. Dynamic memory allocation gives a programmer much more flexibility, in that it allows you to request a specific amount memory to be allocated on the heap, so that it will not disappear with the stack frame of the calling function.

So far, we have focused exclusively on programming in the small—designing the algorithm for a small-sized task, implementing it, testing it, and debugging it. This module discusses three main differences that "real" programs exhibit. 1) They tend to be much larger than those we have written. 2) More than one person works on them, sometimes teams of hundreds to thousands. 3) Real software has a long life-span during which it must be maintained. Now that you have an understanding of the basics of programming in the small, we are ready to begin learning about programming in the large!