Think-Like-a-Programmer
INTRODUCTION
Do you struggle to write programs, even though you think you understand programming languages? Are you able to read through a chapter in a programming book, nodding your head the whole way, but unable to apply what you’ve read to your own programs? Are you able to comprehend a program example you’ve read online, even to the point where you could explain to someone else what each line of the code is doing, yet you feel your brain seize up when faced with a programming task and a blank screen in your text editor? You’re not alone. I have taught programming for over 15 years, and most of my students would have fit this description at some point in their instruction. We will call the missing skill problem solving, the ability to take a given problem description and write an original program to solve it. Not all programming requires extensive problem solving. If you’re just making minor modifications to an existing program, debugging, or adding testing code, the
xiv Introduction
programming may be so mechanical in nature that your creativity is never tested. But all programs require problem solving at some point, and all good programmers can solve problems. Problem solving is hard. It’s true that a few people make it look easy— the “naturals,” the programming world’s equivalent of a gifted athlete, like Michael Jordan. For these select few, high-level ideas are effortlessly translated into source code. To make a Java metaphor, it’s as if their brains execute Java natively, while the rest of us have to run a virtual machine, interpreting as we go. Not being a natural isn’t fatal to becoming a programmer—if it were, the world would have few programmers. Yet I’ve seen too many worthy learners struggle too long in frustration. In the worst cases, they give up programming entirely, convinced that they can never be programmers, that the only good programmers are those born with an innate gift. Why is learning to solve programming problems so hard? In part, it’s because problem solving is a different activity from learning programming syntax and therefore uses a different set of mental “muscles.” Learning programming syntax, reading programs, memorizing elements of an application programming interface—these are mostly analytical “left brain” activities. Writing an original program using previously learned tools and skills is a creative “right brain” activity. Suppose you need to remove a branch that has fallen into one of the rain gutters on your house, but your ladder isn’t quite long enough for you to reach the branch. You head into your garage and look for something, or a combination of things, that will enable you to remove the branch from the gutter. Is there some way to extend the ladder? Is there something you can hold at the top of the ladder to grab or dislodge the branch? Maybe you could just get on the roof from another place and get the branch from above. That’s problem solving, and it’s a creative activity. Believe it or not, when you design an original program, your mental process is quite similar to that of the person figuring out how to remove the branch from the gutter and quite different from that of a person debugging an existing for loop. Most programming books, though, focus their attention on syntax and semantics. Learning the syntax and semantics of a programming language is essential, but it’s only the first step in learning how to program in that language. In essence, most programming books for beginners teach how to read a program, not how to write one. Books that do focus on writing are often effectively “cookbooks” in that they teach specific “recipes” for use in particular situations. Such books can be quite valuable as time savers, but not as a path toward learning to write original code. Think about cookbooks in the original sense. Although great cooks own cookbooks, no one who relies upon cookbooks can be a great cook. A great cook understands ingredients, preparation methods, and cooking methods and knows how they can be combined to make great meals. All a great cook needs to produce a tasty meal is a fully stocked kitchen. In the same way, a great programmer understands language syntax, application frameworks, algorithms, and software engineering principles and knows how they can be combined to make great programs. Give a great programmer a list of specifications, turn him loose with a fully stocked programming environment, and great things will happen.
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