This book assumes a background in the syntax of C++. Coplien shows how to become an expert C++ programmer by learning the idioms of the language. His approach is organized around the abstractions that C++ supports. He shows how these abstractions can be combined to use the language effectively. This book is designed to help programmers who have already learned C++ develop their programming expertise. To understand how programmers achieve proficiency, we need to understand not only how people learn a new language (such as a programming language), but also how a language is used to solve software problems effectively. Learning Programming Languages Not everything you need to know about a product is described in the owner's manual. Before the arrival of our first child, my wife and I were admonished by a friend that no book, and no training, could completely prepare us for the art of parenting. We must of course learn minimal, essential skills. But the interesting, challenging, and rewarding aspects of raising a child go beyond this basic knowledge. For example, no book or "owner's manual" will help you understand why your three-year-old daughter rubs toothpaste in your one-year-old's hair, or why your children hang their socks in the refrigerator. The same is true of programming languages. Programming language syntax shapes our thinking to a degree, but what we learn in the "owner's manual" about syntax alone only gets us started. Most of what guides the structure of our programs, and therefore of the systems we build, is the styles and idioms we adopt to express design concepts. Style distinguishes excellence from accomplishment. An effective parenting style, or programming style, comes from personal experience or by building on the experience of others. A software engineer who knows how to match a programming language to the needs of an application, writes excellent programs. To achieve this level of expertise, we need to go beyond rules and rote, into convention and style, and ultimately into abstractions of concept and structure. It is in that sense that this book is "advanced." The rules, conventions, and concepts of programming drive the structure of the systems we build: They give us a model of how to build systems. A model for problem decomposition and system composition is a paradigm, a pattern for dividing the world into manageable parts. C++ is a multiparadigm language. C programmers use C++ as a better C. Object-oriented advocates do everything polymorphically. In fact, a variety of approaches is usually necessary to express the solution to a software problem efficiently and elegantly. Learning a programming language is much like learning a natural language. Knowledge of basic syntax lets a programmer write simple procedures and build them into nontrivial programs, just as someone with a vocabulary of a few hundred German words can write a story far richer than see-Dick-run. But mastery of language is quite another issue. That such stories are nontrivial does not make them elegant or demonstrate fluency. Learning language syntax and basic semantics is like taking a 13-hour course in German: It prepares you for the task of ordering a bratwurst, but not for going to Germany to make a living, and certainly not for getting a job as a German language journalist or poet. The difference is in learning the idioms of the language. For example, there is nothing in C itself that establishes while (*cp1++ = *cp2++); as a fundamental building block, but a programmer unfamiliar with this construct would not be perceived as a fluent C programmer. In programming, as in natural language, important idioms underly the suitability and expressiveness of linguistic constructs even in everyday situations. Good idioms make the application programmer's job easier, just as idioms in any language enrich communication. Programming idioms are reusable "expressions" of programming semantics, in the same sense that classes are reusable units of design and code. Simple idioms (like the while loop above) are notational conveniences, but seldom are central to program design. This book focuses on idioms that influence how the language is used in the overall structure and implementation of a design. Such idioms take insight and time to refine, more so than the simple notational idioms. The idioms usually involve some intricacy and complexity, details that can be written once and stashed away. Once established, programming language idioms can be used with convenience and power. The Book's Approach Assuming a background in the basic syntax of C++, this book imparts the proficiency that expert C++ programmers gain through experience by giving a feel for the styles and idioms of the language. It shows how different styles let C++ be used for simple data abstraction, full-fledged abstract data type implementation, and various styles of object-oriented programming. It also explores idioms that the core of the C++ language does not