Vol. 1, No. 29
Getting Started With Programming

As we plunge deeper into the complex realm of Web building, the tasks become more and more like programming. HTML jockeys may call themselves "programmers" or "coders," but on the basic level of marking up text, positioning images, and making forms and frames, there's not a lot of genuine programming going on. Mouseover effects and the like are a bit more involved, but programming for real doesn't start until it comes to JavaScript and Perl — code that actually does things based on conditions that the code evaluates, using variables, conditionals, loops, and all the rest of that marvelous business.

To start, let's go over a few of the fundamental concepts of programming, ideas that apply to every programming language. Be patient. If you get the basic ideas in place first, you'll develop good habits (one hopes) and a broad understanding that can be applied to any project, be it the Perl scripts you write for your site's CGI functionality, or obscure, assembly language drivers for obsolete modems.

Unlike, say, writing an e-mail newsletter (about Web-site building), the process of programming should always begin with a clear idea of where you want to end up. Just like you don't just sit down at your favorite editor and start typing HTML, hoping that something will shape up, the more planning you do in advance, the better your code will work out. For example, you know that you want some Perl code that will sort form input based on its content. Start by plotting out in abstract terms just how the code is going to work. Divide up the tasks into blocks. For a program like this, there are at least four discrete steps: accept the input, test the input to see how it should be sorted, evaluate the results, and file the output appropriately.

Once you've got the procedure sketched out, you can get down to work on the various phases. It's a lot easier once you know where you're headed.

Variables

Variables are one of the fundamental elements of almost all programming. It's safe to say that without variables there'd be no computers. Variables are basically little storage units with numbers or strings of characters assigned to them, that are then manipulated in dozens of clever ways. So when you say something like "cans = 6," you are setting the variable "cans" equal to 6. By doing this, you can write a program that tracks soda usage using that variable: Each time one is drunk, the program executes the instruction "cans = cans - 1." That is, the number of cans is reduced by one.

It's a good idea, as in the above example, to give your variables nice, clear, self-explanatory names, so that when you or someone else looks over the code at a later date, you know what is going on. It's no fun to read over your own code a year later and try to remember what the difference was between variables that you named "strghty" and "strgthy."

Conditionals and Functions

Some of the most common techniques you'll find yourself using in your programs are conditional statements: doing one thing if a certain condition is true, and another if it's not. In many programming languages this is done with an "if" statement. It can be something like "if cans = 0 then refill," where "refill" is a function that restocks your fridge with soda.

Functions are isolated, self-contained little bits of code, each one performing a small predefined task when directed to do so. Using functions has the potential to make a programmer's life much easier. Instead of writing the same code a hundred times to do the same simple thing in different places in a program, you can just write it once as a function and then call it whenever you need it. This is called "code reuse" and is smiled upon by the gods of programming.

Typically when you invoke a function, you give it "arguments." No, not in the sense of picking a fight — these arguments are parameters that change each time the function is used. It's not clear why they're called arguments, as they have nothing to do with arguing. Each function is set up to expect a certain type of argument, and that argument is usually what the function works on. So for example, if you have a function that reverses text and the function is called "reverse," the line of code that invokes the function to reverse the text "Medusa" would look like this: "reverse('Medusa')" and the output of the function would be "asudeM."

These are a few of the fundamentals common to all programming. From here, you should pick a nice language to start learning and experimenting with. JavaScript, Java, and Perl are easy enough and useful for Web-site development, so you might want to start with one of them. Happy coding!

HINTS, POINTERS, AND TIPS 'O THE TRADE:

Like HTML, most programming languages allow you to interpolate comments in your code that have no effect on how the program runs. It is very helpful, for you or anyone else who may be looking at your code, to put in a lot of comments clearly explaining what each section of the program does and how. The more complex the program, the more comments you should include.

Indent for clarity. If you have a function or loop, indent it one tab stop. If there's another loop embedded within the first, indent that another tab stop. That way it's easy to see exactly what happens and when.

Don't expect your programs to work right away, even a little bit. There is a lot of debugging, testing, and reworking involved in even the simplest of projects. Coders must be patient.

In the hot weather, if you only have one fan, it's more effective in the long run to use it to push the hot air out than to blow cool air in.

RESOURCES:

Webmonkey's Intro to Programming

Webmonkey's JavaScript Tutorial

Webmonkey's Intro to Perl for CGI

Handcrafted Archive