Fluent C

Chapter 3. Memory Management

Each program stores some values in memory to use them later on in the program. This functionality is so common for programs that modern programming languages make doing it as easy as possible. The C++ programming language, as well as other object-oriented programming languages, provides constructors and destructors, which make it very easy to have a defined place and time to allocate and clean up memory. The Java programming language even comes with a garbage collector, which makes sure that memory that is not used anymore by the program is made available to others.

Compared to that, programming in C is special in the way that the programmer has to manually manage the memory. The programmer has to decide whether to put variables on the stack, on the heap, or in static memory. Also, the programmer has to make sure that heap variables are manually cleaned up afterwards, and there is no mechanism like a destructor or a native garbage collector, which would make some of these tasks much easier.

Guidance on how to perform such tasks is well scattered over the internet, which makes it quite hard to answer questions like the following: “Should that variable go on the stack or on the heap?” To answer that as well as other questions, this chapter presents patterns on how to handle memory in C programs. The patterns provide guidance on when to use the stack, when to use the heap, and when and how to clean up heap memory. To make the core idea of the patterns ...