And then there' this:

Hack Attack Closes Al-Jazeera Web Site

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By Peter Svensson -- AP

March 26, 2003 |

The Web site of Arab satellite television network Al-Jazeera, which has been plagued by hacking attacks since it showed pictures of dead U.S. soldiers in Iraq, was largely unavailable in the United States on Wednesday.

The outage was at least partly due to an apparently defensive move by Al-Jazeera's Web host, according to Brian O'Shaughnessy at VeriSign Inc., which runs many of the servers that guide Web traffic.

Al-Jazeera's Web host changed data on servers used to direct Web visitors to the site, perhaps in an attempt to protect itself against hacking. The move left many Web browsers unable to find the site.

The Web host, based in the Persian Gulf state of Qatar, would not comment on the outage, saying it did not discuss matters concerning clients.

Keynote Systems Inc., a company that tracks Web performance, said it succeeded in fewer than 1 percent of its attempts to reach Al-Jazeera's English-language site from different locations in the United States. The Arabic site was only available 5 percent of the time.

Al-Jazeera, also based in Qatar, is an unusually independent voice in the Arab world. It angered many Americans after it broadcast images of U.S. prisoners and war dead.

When the machine compiles your code, however, it does a little bit of translation. At run time, the computer sees nothing but 1s and 0s, which is all the computer ever sees: a continuous string of binary numbers that it can interpret in various ways.

But some variables are immortal. These variables are declared outside of blocks, outside of functions. Since they don't have a block to exist in they are called global variables (as opposed to local variables), because they exist in all blocks, everywhere, and they never go out of scope. Although powerful, these kinds of variables are generally frowned upon because they encourage bad program design.

We can see an example of this in our code we've written so far. In each function's block, we declare variables that hold our data. When each function ends, the variables within are disposed of, and the space they were using is given back to the computer to use. The variables live in the blocks of conditionals and loops we write, but they don't cascade into functions we call, because those aren't sub-blocks, but different sections of code entirely. Every variable we've written has a well-defined lifetime of one function.

This is another function provided for dealing with the heap. After you've created some space in the Heap, it's yours until you let go of it. When your program is done using it, you have to explicitly tell the computer that you don't need it anymore or the computer will save it for your future use (or until your program quits, when it knows you won't be needing the memory anymore). The call to simply tells the computer that you had this space, but you're done and the memory can be freed for use by something else later on.

That gives us a pretty good starting point to understand a lot more about variables, and that's what we'll be examining next lesson. Those new variable types I promised last lesson will finally make an appearance, and we'll examine a few concepts that we'll use to organize our data into more meaningful structures, a sort of precursor to the objects that Cocoa works with. And we'll delve a little bit more into the fun things we can do by looking at those ever-present bits in a few new ways.