Coding Well Forum

Intro To Programming: Chapter 1 (What is a program?)

So you want to become a programmer, or just want to know what the hell a programmer thinks about...

Well, lets start off with what a program is. A program is a set of instructions that are performed by a computer that input from devices like the keyboard, mouse, storage medium, mic, etc... and output to the monitor, printer, speakers, network, storage medium, etc... whilst doing something in-between.

So then the question is what does a computer understand? The computer understands binary (1's & 0's) where sets of bits (a single 1 or 0) represent different commands. Because humans prefer more readable methods of writing their programs down, the assembly language was created which contains abbreviations to represent commands, such as PUSH, POP and MOV. These commands are very simplistic and don't do much meaning it can take hundreds of lines of code to do a simple math operation. Because of this, higher level languages were built that could group commands to perform common tasks and when you compiled your program, the compiler would do the dirty work of writing the assembly for you.

We will be talking about these higher level languages in the rest of the chapters. Stay Tuned

Intro To Programming: Chapter 2 (The world of variables)

Variables are one of the most important peices of programming because they allow you to store information. It's like a white board where you can write whatever you want but its erased at the end.

So lets say we wanted to store something and put it in a variable (or write it on the white board) and wish to access it later. Well if you just wrote it anywhere and there was a trillion other things on it, you may have a hard time finding it when you need it later, so areas are allocated to you. That way you can find stuff when you need it and you won't interfere with bob who may also be using the whiteboard.

But what if you tried add some info to what was already there and it didnt fit? You can't just erase and make room (bob might get pissed if you erased his stuff and didn't tell him, or worse what if you took memory that controlled what was printed to the screen?), you must allocate enough room to start with, or allocate a bigger chunk somewhere else when you need it.

Some languages let you do whatever wherever and in such cases you can really screw things up if you don't know what your doing. For our purposes here we will assume your not dealing with that crap and are simply letting the language figure it out.

In short, variables vary.

Advanced

This information is stored in memory as bits, 1's and 0's. Typicly, groups of 8 bits (a byte) are used. 256 different combinations can be made with 8 bits. If you need more, you add another byte.

The same byte cannot be used for different variables. If you want to store a True or False value in a variable, it will take a whole byte.