Author: David

Actually going schemaless in C#

Actually going schemaless in C#

JSON Image
Image from json.org

Back in August I talked about going schemaless and I’ve made some progress since then. I’ve created a number of C# classes, many of which include single and in one cases a 2D array of things I want persisted to disk.

I use JSON (JavaScript Object Notation) files to hold the data.  So long as I’ve defined those classes with Properties using Get and Set, the JSON converters in .NET handles it all very nicely.

For example, in my game I have a CityArea class which includes a List<BuildingType> as well as several public properties.

This saved out as JSON like this:

[
  [
    {
      "buildings": [
        {
          "Name": "College",
          "Size": 2,
          "Percent": 60,
          "Cost": 50,
          "Type": 11
        },
        {
          "Name": "Gallery",
          "Size": 2,
          "Percent": 40,
          "Cost": 150,
          "Type": 23
        },
and ends...
      ],
      "State": "R",
      "Type": "F",
      "Density": "L",
      "Points": 46,
      "AreaName": "Newfane"
    },

The whole JSON file has 1500 buildings scattered amongst 100 areas (10 x 10) and is 11422 lines long. The file is 234Kb long. Though that’s with indentations. I could remove that but for now, during development, it makes the file easier to read.

These are the two class definitions (I’ve removed extraneous stuff from them),

class BuildingType : ICloneable {
        public string Name { get; set; } = "";
        public BuildingSize Size { get; set; } = BuildingSize.bsNone;
        public int Percent { get; set; }
        public int Cost { get; set; }
        public BuildType Type { get; set; }
}

class CityArea {
        public char State { get; set; }
        public char Type { get; set; }
        public char Density { get; set; }
        public int Points { get; set; }
        public string AreaName { get; set; }
        public static List AllBuildings = new List();		
}

This is the code to save out areas (which is List<CityArea> areas to the file. I found this by reading the Microsoft documentation about Serialization and deserialization. It’s pretty good stuff and the code for saving these structures are these pretty short methods.

        public bool SaveToUTF8(string filename)
        {
            var options = new JsonSerializerOptions
            {
                WriteIndented = true
            };
            var bytes = JsonSerializer.SerializeToUtf8Bytes(areas, options);
            File.WriteAllBytes(filename, bytes);
            return true;
        }

and this is the code to Load it.

        public bool Load(string filename)
        {
            try
            {
                var bytes = File.ReadAllText(filename);
                areas = JsonSerializer.Deserialize<CityArea[][]>(bytes);
            }catch(Exception e)
            {
                Error = $"Failed to load {filename} because {e.Message}";
                return false;
            }
            return true;
        }

I haven’t timed either Load or Save but they are fractions of a second.

Fascinating look at the BBC Micro game Elite

Fascinating look at the BBC Micro game Elite

BBC Micro EditeThis is somewhat off-topic and a little bit of self-indulgence because (a) it’s about a computer that existed over 36 years ago and (b) a game that was programmed in 6502 assembler. It’s also a game I played a lot back in 1984.

The reason for including it here is because a British Web Developer called Mark Moxon has created an excellent website about the game, looking at the algorithms, source code etc. of the BBC Micro version of Elite. Everything you wanted to know about how it works.

I’d sum up this website as the “Cliff’s Notes” to the BBC Micro version of Elite. Be sure to click the three bars at the top left as the Navigation Bar gives an idea of just how much there is in this website. There’s bit by bit breakdowns of variables for example, in generating System Data.

Government
  ----------
  The government is given by a 3-bit value, taken from bits 3-5 of w1_lo. This
  value determine the type of government as follows:
  
    0 = Anarchy
    1 = Feudal
    2 = Multi-government
    3 = Dictatorship
    4 = Communist
    5 = Confederacy
    6 = Democracy
    7 = Corporate State

This is a remarkable piece of work, I can’t imagine how many hours Mark has put into it. Possibly as many as it took to develop the game originally!

Where do I get a lot of my information from?

Where do I get a lot of my information from?

SubredditsI was asked this a few months ago. There are various sources including Hackers News and Reddit.com. But reddit is just a collection of specialised sub communities (known as Subreddits) and even I wasn’t aware of quite how many there are.

I came across a link which lists 43 programming related subreddits. On the right hand bar there’ a list of a few Subreddits but at the bottom there’s a View More link to show all 43.

I’ve shown them here to give you an idea of what’s available. The member numbers will change and are often out of date anyway.

Tutorial 3 on Enum variables published

Tutorial 3 on Enum variables published

Magic Numbers
Image by John Hain from Pixabay

This is the third in a series of C Tutorials that I originally published on about.com between 2006 and 2013.  I’m republishing them on here. This time it’s about enum variables. While these aren’t anywhere as important as say in C++ or other languages (because C’s type checking is not great!) they make the program more readable.

I see them as banishing magic numbers. A magic number is a number in a program that is just there. Like when you declare an array and use the number 20. That is a magic number and it would be better if there was a #define NUMBERMONSTERS 20.  This avoids the problem of your program being full of 20s until one day you change it to 30 but manage to miss a couple of them and you introduce bugs. By using NUMBERMONSTERS everywhere you can change it in just one place (at the #define) and avoid the problem of missing.

Enum variables are similar. Behind the scenes they are just ints. In other programming languages like C++, Pascal, C#, the compiler enforces the enum values. In those languages you can’t declare an enum variable then assign any int value to it, but in C you can.  But they can at least make your program more readable.

The picture? Magic numbers!

To brace or not to brace

To brace or not to brace

Abstract programming picture
Image by Gerd Altmann from Pixabay

This isn’t exactly confined to C, in fact it applies to many programming languages where braces or curly brackets {like this} are optional after an if. It even applies to Pascal with Begin ends which are optional after an if.

You can have the first or the second as shown below.

if (expressions) 
  DoSomething;

if (expression {
  DoSomething;
}

I saw a recent example where the DoSomething was a logging expression which the compiler optimised away so the if, which lacked braces applied to the next statement. As the if was only true on rare occasions. It meant that that statement which should have been run every time was only run on those rare occasions.

So the prevailing wisdom and one that I entirely agree with is that you should always use braces. If you don’t you risk accidentally introducing bugs like this.

Note. that link is to a discussion on the C programming Subreddit (on Reddit.com).

.

A lovely MiniGolf game in C

A lovely MiniGolf game in C

MiniGolfA developer called Michael Gerdes just published a MiniGolf game on GitHub. This uses OpenGL for the graphiocs and according to GitHub is made up of

  • C 76.5%
  • C++21.4%
  • GLSL 0.8%
  • Scheme 0.7%
  • Objective-C 0.6%
  • HTML 0.0%

Every project on GitHub has these on the RHS of the home page. They include links with filters to see the particular set of files. Particularly telling is GLSL which are shaders. If you do 3D graphics, that’s something you need to learn. Its why I stick to 2D. The other stuff probably comes as part of various linked libraries.

It’s nicely done and the GitHub page has four animated gifs showing how it works. It also uses the open source Dear Imgui GUI library.

A portable Windows Devkit

A portable Windows Devkit

Tool icons
Image by mohamed Hassan from Pixabay

I spotted this the other day. A C and C++ development distribution for Windows called w64devkit. It’s less than 80 MB and you don’t need to install it so you could easily fit it onto a USB memory stick or download it.

As the author (Chris Wellons) says “Despite its simple nature and small packaging, w64devkit is almost everything you need to develop any professional desktop application, from a command line utility to a AAA game”. Note it doesn’t include source control, nor does it access the internet, though no doubt you could. So you could backup stuff say to GitHub or wherever.

I am fan of software like this that you can take with you on a laptop or a memory stick. You don’t always have to have a full dev system with multiple monitors, Visual Studio etc.

If you’re interested, do read the entire blog post.

 

First C Tutorial published

First C Tutorial published

TutorialAs I add these (one or two each week), I’ll add them to the tutorials page. The first is introducing C Programming and has the almost mandatory Hello World.  To speed up trying the code out, I’ve included links to two online C compilers where you can run the program.

The two online compilers Ideone.com and Codepad.org were both around when I wrote the original tutorial and the original C program (Ideone) link still exists on Ideone. (After you compile a program successfully they provide a shortcut back to it).

I’ve taken the original C tutorials and have stripped all the cruft (CSS, much Html, and JavaScript) and edited slightly).  It helps that I wrote them originally back around 2006-2007. There’s approximately 30 in total. I will be beefing them up as well.

Follow the Tutorials link on the top menu.

My earlier work in C, C++ and C#

My earlier work in C, C++ and C#

Cplus.About.com screenshotThe tutorials I wrote on C++ and C# on cplus.about.com between 2006 and 2013 are all a bit dated now. Both languages have been updated several times since 2013 when I stopped writing for About.com. But thanks to the Wayback machine you can view all of my work from the early stages in Mid 2006 to the finish in July 2013.  I owe the copyright to this material so I can reuse it as I wish.

On this page, there’s an index to 43 C tutorials, most written by me.  So as a little side task, I’m downloading these, cleaning them up, fixing the odd error and adding them to this website via the Tutorials page. Some but not all are also available on the ThoughtCo website which is the reinvention of About.com.

Ironically I got better at writing for them towards the end. About.com had been very successful back in the late 90s when the web was still fairly new but could never sustain that and declined more or less from the year 2000. I think the highest daily viewing figure I ever got was 12,000 pages but some of the others (particularly Southern Cooking) got in the millions.

I recommend you visit archive.org earlier in the day as it slows up a bit once the USA wakes up typically around 1.00 PM (GMT). Given the volume of stuff it stores, it is a totally amazing place.