lesson 02- Setting up the Environment in C

setting up the environment in C

Part 2: Setting up the Enviroment

Before we can start programming, we obviosuly have to have the requiered programs to start programming right? This section will cover the required software to begin following along. It will also cover some of the basics of how a C program is made.

Creating a program in C

Before I cover the requiered tools to start writing code, I briefly want to touch on how a program is even made in the first place. Doing this will help you to have more of an understanding of why we have the tools that we have. BEFORE WE GO ANY FURTHUR, all of these tutorials will be using Windows, if you want to follow along on Linux or some other platform, most of the code will work fine (minus any Win32 stuff we use way later on) but the process of converting your code to an executable will be different, so you need to keep that in mind as we go through these tutorials. 

Compilation, Executables, and Other Stuff.

Alright,so lests begin. Let's start with a program is. Whenever you run a program on your computer, a lot is actually happening, and you can get into pretty low level minutia about how all of that works, so instead of getting crazy technical, I'll do a more broad overview. So when you first open a program, a program called the "Kernel", loads the program into memory. When the program gets loaded, there are typically different dependencies that it has, such as a library it needs to get data from, etc. These libraries are called "DLL's". The kernel goes through and finds the dll's the program needs to run and allocates memory for those along with the main program. Now we havn't covered functions yet, so I'll try to word this differently, but essentially your main program will typically make calls to various sections of code within each dll. The kernel goes through and it stuffs in the memory addresses of each of those functions contained within the dll into your actual program memory. This is just the basics of how an executable actually get's started; the actual running of the program will depend on the language/compiler used/etc. So how do you get a program in the first place? Well, you write some code and compile it. 

    Compilation; (compiling) involves taking a set of ASCII text (ASCII is a form of character encoding, or if that makes no sense, think of it as a specification for how to convert binary to readable characters, ASCII is a version of this) that then get's fed into a "Compiler". The compilers job is to take this code and produce an executable by reading in the code you wrote. This essentially converts the code down to assembly that runs on the chipset you are on, and it does a slew of other things as well that are outside of the scope of how deep I'm going to get. At this point you may be asking something like "Well, where does C come in?", and that's a valid question. Here's the thing, for all intents and purposes, there is no such thing as a "C language", there is merely a compiler. See, what happens is when you write a language, you are actually writing a program (compiler) that will read characters in certain sequences and spit out assembly accordingly. Now, for this reason, there is an organization called ANSI, which is the American National Standards Institute. These are the people in charge of setting the specification of the C language (among other languages), which will tell anybody who ships a C compiler how their compiler must function. You may come across the terms ANSI C, C99, etc. These are standards of the C language. 

So what do I need?

I thought you would never ask! To begin programming is quite trivial actually, you will need two programs and a computer that is operational to some degree (I'll assume you have the third). The first program you will need is some sort of text editor, you can use literally anything, but I'm going to make a few suggestions:

NotePad++ Is a pretty powerful text editor that is completely free, it offers some syntax highlighting and intellisense (if you don't know what that means, just know that it's really useful.) Download Link Here

Atom is a free text editor distributed by GitHub, it is a pretty decent little editor and it has some nice features, I'm actually writing this as we speak in Atom (I'm playing around with it). It's hackable to the core and it has a lot of community backing it and creating add ons for it. Download Link Here

Visual Code is Microsofts response to open source text editors, it's not a bad editor, and it is open source and cross platform (as are the other two) so it's not too shabby. It is still in beta, so it's a bit buggy at the moment, but still totally useable (that said, it's at version 0.8.0, so by the time this is released it may be out of beta...), I enjoyed writing code with it. Download Link Here

There are several other editors you can use, such as Emacs and VIM, I just think that these editors have a very high learning curve so I'm not going to recommend them to people who have never even programmed before, because as a beginner you won't get much use out of the advanced features anyways.

    The; final thing you will need is a C compiler. Again, we are using windows, so if you are on another platform, you will need to find another compiler. As an aside, all of our early on compilation will be via the command line just so people are aware. I feel that learning command line first is a very good idea and it is generally just a better way of compiling code honestly, and not just for C; alot of things in say C# are best done with the command line, so if you have experience doing compilation with the command line you will be in good shape. Anyways! so, sorry in advance to any Visual Studio haters, but it is the compiler of choice on Windows so...suck it up. We'll be using the Visual Studio Visual C++ compiler. But wait, I thought that this was a C tutorial?? It is, C++ is C with object orientation added on, and so if you put C code through a C++ compiler, it will compile properly, which means you can easily learn C++ once you know C (Add that to perks of learning C). Anyways, go through the steps of getting it downloaded and we can move on to the annoying part of getting set up, which is getting the command line ready to be used. Here is the link to the download, notice this is a link to the download for Visual Studio, this is because Visual Studio comes with the compilers you want (C#, F#, C++, Basic (not that you'd ever want to touch that) etc.) and plus we will be using Visual Studio for debugging purposes eventually and hey, I may even show you guys how to use Visual Studio for compiling code as well, but that will be later on, so you may as well download it now. Another thing, this is the community edition, Visual Studio comes in different versions, so Community is a free version of Visual Studio that is a bit better than the regular free version, but with less features than the ultimate edition (very expensive). Now at the time of writing this, this version is still free, if it is not, go and download the express version of Visual Studio, it will work just fine. 

Setting up the command line

First order of business, you need to figure out where your command prompt is and put it somewhere accessible, I have mine on my taskbar so it's always right there. Open it and take a good look at it, very bland right? Boring, un-inspired, dull, stab my eyes out ugly. Fortunately, we can make this look a little nicer. Right click the command prompt icon and click properties, you will have two tabs you can play around with that will let you really customize the look, the font tab and the colors tab. These will help you want to kill yourself a little less while looking at your command prompt. This is how mine looks if you are interested, I am using Red 235, Green 140, and blue 80 for the text color, and size 16 Consolas font with bold checked on.

    Next; up, we need to learn how to actually invoke the compiler, afterall being able to use it is pretty important. Now I could go on for a while as to why this is how it is, but I'm going to spare you guys the rant and just leave it at this: As little sense as it makes as to why Microsoft sets up the compiler the way that they do, there are some historical reasons as to why it is how it is...you'll just have to take my word for it. With that warning, let's get to it. Before I teach you how to set it up you'll need to know a few commands to actually navigate, the main two being "cd" and "dir", typing dir will tell you what files are located in your current working directory, so for example, if I am in the C drive and I type dir, I get the result in the picture from earlier. The other command is "cd", this command is how you navigate to a new directory. To do this, you type "cd (filename)", so for example if I want to navigate to program files from my C drive I would type "cd Program Files". Note that these file names are not case sensitive, this is a Windows thing, unless I am in error I believe Linux and Mac OS are case sensitive so keep that in mind. Lastly, if you want to navigate backwards you type "cd ..", and if you want to navigate back multiple files you type "cd ../../../", each slash signifying the number of directories you wish to go back.

    Alright;, now we are ready proper to get the compiler set up. First off, you will need to locate where you downloaded Visual Studio. In general, it should be under the path name "C:\Program Files (x86)\Microsoft Visual Studio 12.0\vc", however I can't guarentee this, but it will for sure be in the Microsoft Visual Studio (version number) folder. The vc part of that file name is the actual Visual C++ compiler folder. Within this folder is something called a bat file. A bat file is (usually) a simple script that you run to do something. Now, when you get to this directory, type dir and you should see a file called vcvarsall.bat. This is the important file we need. Essentially what this file is going to do for us is let us use the C++ compiler no matter what directory we are in. This is one of those moments you wonder why they didn't just have this run everytime the command prompt is opened, but I digress. Now, type the following command "vcvarsall.bat x64". What this is going to do is set up the 64 bit version of the compiler, essentially you can pass what's called a flag to the bat file, flags in terms of the command line just mean you turn on or off certain settings. If you simply ran the bat file I believe it would default to the 32 bit version of the compiler, don't quote me on that. Now I want you to close the command prompt and re-open it..................Did you do it.....?

Great, so heres the fun part about Microsoft, that bat file only lasts for the the duration of the command prompt session you are in, so when you close it, you have to set all of that stuff up again. fun right?? 

    What; we are going to do is create our own bat file, and we're going to call this bat file "Startup.bat", this will be a very simple bat file that will simply run when we open the command prompt, and it will call vcvarsall.bat so that every time we open the command prompt, it sets up the C++ compiler by default. I recommend putting this file in your C drive, but do whatever you want, just make sure you know where it is at. Open a new notepad document and type the following:

@echo off

call "C:\Program Files (x86)\Microsoft Visual Studio 12.0\vc\vcvarsall.bat" x64

                         

Obviously if you're path name is different change the directory. Now, save this to wherever you want as "StartUp.bat". Now, right click the command prompt icon and click properties. There will be a section under the shortcut tab that says "target". put this in there 

%windir%\system32\cmd.exe /k "c:\startup.bat"

                         

Again, the directory should be changed to whatever you chose for it to be. So this will set up the compiler every single time we run the command prompt. If you would like to, you can also set the default location to start in by specifying the path of a certain folder in "start in", this means when you open the command prompt it will set up the compiler for you and put you into the directory you are doing most of your work in, which is pretty dang nice if I do say so myself. 

A Few Last Things

I know this has been a lot of work just to set up a stupid compiler, but I promise it's well worth it, plus we're almost done! Alright, create a folder for the code examples we'll be doing and name it whatever you want. This is the folder I've set my start location to, obviously you can do whatever you want but it would probably be a good idea to do this as well. In this folder, I want you to create a folder for each lesson we do, this will force you to modify the bat file and keep the build process fresh in your mind as we go through each tutorial. I've created a folder called Lesson1 for when we do our first programming lesson. In each lesson folder, you will follow the same format, a folder called "code" and a folder called "build", the code folder will hold any source code and our build bat file. The build folder will hold our actual output files from each build, including debug information and the actual executable. Now, the only thing you should need to change for each lesson is the folder the bat file is referencing. So, in your code folder for Lesson 1, open notepad, and copy this (Make sure that everything is on the correct line, I've identified where to start a new line with a * character)

@echo off*

*

mkdir ..\build*

pushd ..\build*

cl -Zi c:\CWebsiteTutorials\Lesson1\code\main.cpp user32.lib gdi32.lib*

popd*

                         

So this looks confusing, but it's not. Line 2 says "if there is no directory called build, make a directory called build". Next line 3 says "Now, go to this build folder as the current working directory." Line 4 uses a command called cl. This is the command you use to invoke the C++ compiler, so whatever file you type after is the file it will compile. The user32.lib and gdi32.lib are libraries that I've decided to include for when we do Win32 later on. GDI is how you do graphical stuff in C. You'll also notice I've passed a flag (whenever something has a - next to it, it's a compiler switch, meaning a setting you can turn on or off), this flag is Zi, and it means give me debug information. if you don't want debug information, you simply don't use the compiler switch. Important side note, MAKE SURE that you're file names don't have spaces in them, it will screw up the compiler when it tries to find your file. So name your file Lesson1. Now, save this file as Build.bat in your code folder, and open the command prompt and navigate to the code folder. In this code folder, add a new notepad document and type the following code (And yes, I do mean type it, don't copy and paste, get used to typing things like a programmer, because progammers have a whole different set of keys we care about).

#include <stdio.h;>

int main()

{

  printf("Hello World!");

  getchar();

  getchar();

  return 0;

}

                         

This is what we refer to as a "Hello World" program, it's the typical first program. Save this file as "Main.cpp", and yes, name it exactly that or you'll need to modify the bat file. Now, using the command prompt and while you are in the code folder, type "build"; this will run your build.bat file for you. You should see a bunch of stuff pop up and then nothing. Back out to your build folder and type dir, the thing you care about is "main.exe". Congratulations, you have compiled your first C program. If you type main, it will run the program in the command prompt. It should output "Hello World", and wait for you to press a key twice. Alright, that's it, your enviroment is now completely and utterly set up, you will never ever have to redo this ( unless you get a new computer or wipe your hard drive or something like that. ). The only modifications you will ever need to make are when you create new folders for each lesson you'll have to edit the built.bat file to point to the new directory. I will explain this for the first few lessons but then it's up to you to remember to do it. 

Conclusion

So, I know this was a LOT of work, it probably was very tedious, but hopefully my instructions all made good sense and you didn't have a bunch of weird errors pop up. Think about this though, you've gone from (possibly) knowing nothing about programming or the command line to understanding how to set up your own build system to compile programs, bat files, how the command line works, how the C++ compiler works at some level, how the OS handles loading your executable, and a few other things. Not bad for just setting up your enviroment I'd say. In the next lesson, we will disect the program you wrote and learn about what each thing is and how it works. 

Lesson1: A briefoverview of the Language: Lesson3: Hello World in C