AKMA’s Random Thoughts

http://www.canada.com/saskatoon/story.asp?id={CC652EE5-C444-4902-B6FA-9BC74F9F1CCA} - the dark side of Digital ID theft.

Each Stack Frame represents a function. The bottom frame is always the main function, and the frames above it are the other functions that main calls. At any given time, the stack can show you the path your code has taken to get to where it is. The top frame represents the function the code is currently executing, and the frame below it is the function that called the current function, and the frame below that represents the function that called the function that called the current function, and so on all the way down to main, which is the starting point of any C program.

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.

This back and forth is an important concept to understand in C programming, especially on the Mac's RISC architecture. Almost every variable you work with can be represented in 32 bits of memory: thirty-two 1s and 0s define the data that a simple variable can hold. There are exceptions, like on the new 64-bit G5s and in the 128-bit world of AltiVec

The most basic duality that exists with variables is how the programmer sees them in a totally different way than the computer does. When you're typing away in Project Builder, your variables are normal words smashed together, like software titles from the 80s. You deal with them on this level, moving them around and passing them back and forth.

This back and forth is an important concept to understand in C programming, especially on the Mac's RISC architecture. Almost every variable you work with can be represented in 32 bits of memory: thirty-two 1s and 0s define the data that a simple variable can hold. There are exceptions, like on the new 64-bit G5s and in the 128-bit world of AltiVec

Being able to understand that basic idea opens up a vast amount of power that can be used and abused, and we're going to look at a few of the better ways to deal with it in this article.