Effective C++, Third Edition

3. Resource Management

A resource is something that, once you're done using it, you need to return to the system. If you don't, bad things happen. In C++ programs, the most commonly used resource is dynamically allocated memory (if you allocate memory and never deallocate it, you've got a memory leak), but memory is only one of many resources you must manage. Other common resources include file descriptors, mutex locks, fonts and brushes in graphical user interfaces (GUIs), database connections, and network sockets. Regardless of the resource, it's important that it be released when you're finished with it.

Trying to ensure this by hand is difficult under any conditions, but when you consider exceptions, functions with multiple return paths, ...