AKMA’s Random Thoughts

Yes!

Go you, AKMA!

Oh yeah.

Admit it, you love to split hairs.

Not that there's anything wrong with that.

My tweak: "Everything fits and is comfortable and you feel fabulous."

Seth Roby graduated in May of 2003 with a double major in English and Computer Science, the Macintosh part of a three-person Macintosh, Linux, and Windows graduating triumvirate.

When compared to the Stack, the Heap is a simple thing to understand. All the memory that's left over is "in the Heap" (excepting some special cases and some reserve). There is little structure, but in return for this freedom of movement you must create and destroy any boundaries you need. And it is always possible that the heap might simply not have enough space for you.

This variable is then used in various lines of code, holding values given it by variable assignments along the way. In the course of its life, a variable can hold any number of variables and be used in any number of different ways. This flexibility is built on the precept we just learned: a variable is really just a block of bits, and those bits can hold whatever data the program needs to remember. They can hold enough data to remember an integer from as low as -2,147,483,647 up to 2,147,483,647 (one less than plus or minus 2^31). They can remember one character of writing. They can keep a decimal number with a huge amount of precision and a giant range. They can hold a time accurate to the second in a range of centuries. A few bits is not to be scoffed at.

When a variable is finished with it's work, it does not go into retirement, and it is never mentioned again. Variables simply cease to exist, and the thirty-two bits of data that they held is released, so that some other variable may later use them.

Note first that favoriteNumbers type changed. Instead of our familiar int, we're now using int*. The asterisk here is an operator, which is often called the "star operator". You will remember that we also use an asterisk as a sign for multiplication. The positioning of the asterisk changes its meaning. This operator effectively means "this is a pointer". Here it says that favoriteNumber will be not an int but a pointer to an int. And instead of simply going on to say what we're putting in that int, we have to take an extra step and create the space, which is what does. This function takes an argument that specifies how much space you need and then returns a pointer to that space. We've passed it the result of another function, , which we pass int, a type. In reality, is a macro, but for now we don't have to care: all we need to know is that it tells us the size of whatever we gave it, in this case an int. So when is done, it gives us an address in the heap where we can put an integer. It is important to remember that the data is stored in the heap, while the address of that data is stored in a pointer on the stack.

Earlier I mentioned that variables can live in two different places. We're going to examine these two places one at a time, and we're going to start on the more familiar ground, which is called the Stack. Understanding the stack helps us understand the way programs run, and also helps us understand scope a little better.