Can someone tell me the very basics of how computer programming works? [closed]

Answer 1

The CPU has a register (a thingy that can store a number) called an instruction pointer. The instruction pointer says what address in memory to pull an instruction from. The CPU pulls an instruction, executes it, and goes on to the next instruction, unless the instruction that it executed said to go somewhere else. These instructions are fairly weak. Add this number to that number. Store this number over there. Take the next instruction from over there. A program called a compiler analyzes your program and turns it into machine code (I'm skipping a few steps here).

Two books that will give you a decent overview of this process are SICP and TECS.

Answer 2

You could compare how programming works to translating between languages. Say you were on a desert island with 2 other people. You only speak French. Person number 1 (we'll call him Fred) only speaks French and Japanese. Person 2 (Bob) only speaks Japanese. Say you need to ask Bob to go help you gather some firewood. Imagine in this case you are the program and Bob is the computer. You say to Fred in French "Can you tell Bob to come help me." Fred translates into Japanese and asks Bob to help you. In this case Fred would be the compiler. He translates the request into something Bob can understand. That is sort of how a computer program works.

There is a good How Stuff Works article that explains things.

I personally didn't really understand how computers could work the way they do until I took a digital electronics class. Prior to that the whole idea of how computers could work at all for me. After I built a binary counter it all made sense.

Answer 3

Basically, you start out with something simple such as:

print("Hello World");

Then you simply sprinkle syntactic sugar and magic tokens over it until it does what you want!

Answer 4

A computer programming language is actually a highly abstracted language that is converted down into a very very basic language that computers actually understand.

Basically, computers really only understand machine language, which is a basic language implemented in binary (1's and 0's). One level above this is assembly language, which is a very primitive language that is at least human readable.

In a high level language, we might have something like:

Person.WalkForward(10 steps)

In Machine code it would be:

Lift Persons Left Foot Up
Lean Forward
Place Left Foot Down
Lift Right Foot up
Lean Forward 
Place Right Foot Down
etc

Now obviously, nobody wants to write programs that tell the computer every little repetitive thing to do so we have tools called compilers.

A compiler takes a higher level language that is easier for a human to understand, and converts it down to machine code, so that the computer can run it.

Answer 5

The computer has a preset number of instructions; thing it already knows how to do. A computer program is simply a list of instructions that the computer will execute sequentially.

Early programs were written directly in machine language. Programmers, to make their lives easier, started to create abstractions to simplify the programs they need to write. Over time, more and more abstractions are added, like layers of an onion, but it all boils down to essentially the same thing - executing a series of instructions.

If you want to learn about programming without focusing on compilers, technology, etc, you get a good indication of what a program is when you start to create 3D scenes in Alice. Alice is free from Carnegie Mellon University. You end up learn how to programming without trying to learn proramming.

If however you want to learn more about the technical details, your best bet would be to look at some intro compi-sci university text books. The following How C Programming Works might also give you some answers.

Answer 6

Several people have already provided summaries of the translation process from a typical programming language down to actual machine code that a processor can execute.

To understand this process, it's helpful to have a concrete feel for what it's actually like to program at the level of machine code. Once you have an understanding of what the processor itself can do, it's easier to understand higher-level programming constructs as the abbreviations they are.

But unfortunately, writing machine code for a desktop computer is not much fun.

As an alternative, there is a great old game called Corewar in which you write little programs using a simplified machine language. These programs then battle each other for survival. You can write basic programs in the raw machine language, and then there's a system of macros so you don't have to repeat yourself so much, and that's the first step towards a full-featured language.

Another easy, rewarding, but low-level thing to do is to program a simple embedded controller like an Arduino. There are lots of easy introductions like this one available. You'll still be using a compiler, but the resulting machine code is easier to understand (if you want to) because the capabilities of the processor are so much simpler.

Both of these are great ways to get a feel for how digital computers actually work.