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Computers can understand languages, though in a rather different fashion to how most people do. Being logical devices that cannot understand subtlety or ambiguity, languages such as English and French aren t appealing to computers. Computers require languages with logical structures and a well-defined syntax so that there s a logical clarity in what you re telling the computer to do. Clarity is required because almost everything you relay to the computer while programming is an instruction (or command). Instructions are the basic building blocks of all programs, and for the computer to perform (or execute) them properly, the programmer s intentions must be clear and precise. Many hundreds of these instructions are tied together into programs that perform certain tasks, which means there s little room for error. You also need to consider that other programmers might need to maintain computer programs you ve written. This won t be the case if you re just programming for fun, but it s important that your programs are easy to understand, so you can understand them when you come back to them later on.

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Although English would make a bad programming language, due to its ambiguity and complexity, Ruby can feel surprisingly English-like at times. Ruby is just one of hundreds of programming languages, but it s special because it feels a lot like a natural language to many programmers, while having the clarity required by computers. Consider this example code:

Read through this code aloud (it helps, really!). It doesn t flow quite as well as English, but the meaning should be immediately clear. It asks the computer to 10 times print Hello, world! to the screen. It works. If you ve got irb running, type in the preceding code and press Enter to see the results:

in: The Membership Operator I have already introduced the in operator (in 2, in the section Membership ). It can be used in conditions, just like all the other comparison operators: name = raw_input('What is your name ') if 's' in name: print 'Your name contains the letter "s".' else: print 'Your name does not contain the letter "s".' Comparing Strings and Sequences Strings are compared according to their order when sorted alphabetically: >>> "alpha" < "beta" True If you throw in capital letters, things get a bit messy. (Actually, characters are sorted by their ordinal values. The ordinal value of a letter can be found with the ord function, whose inverse is chr.) To ignore the difference between uppercase and lowercase letters, use the string methods upper or lower: >>> 'FnOrD'.lower() == 'Fnord'.lower() True Other sequences are compared in the same manner, except that instead of characters you may have other types of elements: >>> [1, 2] < [2, 1] True If the sequences contain other sequences as elements, the same rule applies to these sequence elements: >>> [2, [1, 4]] < [2, [1, 5]] True

Hello, world!Hello, world!Hello, world!Hello, world!Hello, world!Hello, world! Hello, world!Hello, world!Hello, world!Hello, world!

of graphics and styles to choose from, and you have to nd the ones that are the best match with both you and your audience. Especially if working with graphics is a new skill for you, this project might feel daunting right now. But think of approaching this task just as you would any other project by rst assessing the current state of the project, then guring out what needs to be done, and then making a plan for how you re going to accomplish that. This chapter will help you through the process of adding graphics to your storyboard step by step, helping you to break up the project into smaller, more manageable tasks.

Note Experienced programmers might wonder why there s no semicolon at the end of the previous code

example. Unlike many other languages, such as Perl, PHP, C, or C++, a semicolon is not needed at the end of lines in Ruby (although it won t hurt if you do use one). This can take a little while to get used to at first, but for new programmers it makes Ruby even easier to learn.