C# Workshop - Week 1 (Ch. 1 & 2) - Advanced - Old Archive

Jeromy Walsh · 2007-07-13T04:01:30

Welcome to the GDNet C# Workshop – Ch. 1 & 2For a complete introduction to this workshop, please look here. Workshop Overview This workshop is designed to aid people in their journey to learn beginning C# (C-Sharp). This workshop is targeted at highly motivated individuals who are interested in learning C# or who have attempted to learn C# in the past, but found that without sufficient support and mentoring they were unable to connect all the pieces of this highly complex but powerful programming language. This is a 'guided' self-teaching C# workshop. Each student is responsible for taking the time to read the material and learn the information. Additionally, this workshop does not attempt to defend C# as a language, nor does it attempt to demonstrate that C# is either more or less useful then other programming languages for any particular purpose. People who intend to start a discussion about the differences between C# and ANY other languages (except as are relevant to a particular discussion), are encouraged to do so elsewhere. This workshop is for educational, not philosophical discussions. Finally, the community and tutors that arise out of this workshop are here for making the learning process run more smoothly, but are not obligated to baby-sit a person's progress. Because everyone will be working from the same references (.NET Book Zero and optionally the C# Language Specification 1.2 & 2.0), students may find it easier to get answers to the specific questions they might have. There is no minimum age requirement, and there is no previous programming experience required. However, we will be moving quickly so it's essential that students stay on task and dont fall behind. Experienced C# Programmers Feel free to post your own additional knowledge about the topics, however please try and keep the information you provide objective. If you MUST provide subjective/opinion-based information, please do so by marking the paragraph with [opinion] tags. This will make it clear to the readers what is fact, and what is opinion. Also, it may be relevant to mark some information with [observation] tags for information which you’ve “observed” but may not be fact. Finally, if you’re providing information which is related to common programming errors, you might tag it with a [warning] tag. Also, feel free to post links to additional resources about the topics for this week. I will do my best to add those to the “Additional Resources” section at the bottom of this post. Quizzes & Exercises Each week I will post review questions and exercises in the weekly thread. Please try and answer them by yourself. Once you've done so, feel free to look over the answers provided by others and submit your own answers if you've not yet seen them posted yet. Discussion about the quiz questions and answers is encouraged for clarification. Finally, experienced C# programmers may feel free to post quiz-like questions and exercises of their own. Chapters 1 & 2 – Introduction & Lexical StructureIntroduction Greetings everyone and welcome to the C# Workshop. This week we begin the workshop with what I effectionately call the "Everything and The Kitchen Sink" chapters. You see, books on programming languages often try and cover tiny bits of information at a time, only showing you the information on a "need to know" basis. However, the majority of programming languages aren't implemented in bite-size chunks. They're complicated, intertwined devices necessarily complex for the purpose of doing complex things. Think about it...would it make much sense to teach English only by teaching the verbs first? "Dont worry, son, these verbs will all make sense when we've learned nouns in a few years." No. It would be frustrating as you wouldn't be able to put the verbs in context. As people who've previously read programming books can testify to, when the information is presented in bite-sized chunks, keeping relevant information from you until later, it's often common to answer questions with yet MORE questions. As well, you often find yourself saying "ooooh, so that's how this is used, I wish I'd known that 5 chapters ago when they first introduced it." With that being said, the C# specification takes a different approach. They give you a complete overview of the entire language, from concept to implementation...in the first chapter. Is this overwhelming? Hell yes. I'll be honest with you, after reading the first two chapters you wont be able to write much more than a "Hello World" program. You're not going to know much about the syntax, however, you'll have received an invaluable survey of the language. As we come upon later chapters where the information in chapter 1 is presented in more depth, the terminology will have more meaning to you after having received this overview. So in spite of the fact that you're likely to read these first two chapters and go uhhh....I dont get it, I encourage you not to give up. The purpose of the first two chapters isn't really to teach you the language, but instead to get you comfortable with the elements that make up the language. It's basically the teacher saying..."Well, this isnt going to teach you English, but...English is made up of Nouns, Verbs, Adjectives, etc..." Outline of the Reading - Chapters 1 & 2 Hello World Program Structure Types and Variables Expressions Statements Classes and Objects Structs Arrays Interfaces Enums Delegates Attributes Programs Grammars Lexical Analysis Tokens Pre-Processing Directives Additional Resources A good general overview of C# is located at the following URL, with decent descriptions and plenty of code samples. I highly encourage all complete programming beginners to check it out. http://www.publicjoe.f9.co.uk/csharp1/csharp03.html Good Luck! [Edited by - JWalsh on July 21, 2007 10:30:37 PM]

alvarofrank

122

July 11, 2007 02:52 PM

i have a hard time understanding the difference between Starting an array like this:

Array names = Array.CreateInstance( typeof(String), 2, 4, 4 );

and like this:

string[,] names = new string[4, 4];i want to use it to insert items in the array:    class MapEngine    {        private byte xMaxArray = 40;        private byte yMaxArray = 40;        public byte ModxMaxArray        {            get { return xMaxArray; }            set { xMaxArray = value; }        }        public byte ModyMaxArray        {            get { return yMaxArray; }            set { yMaxArray = value; }        }        public void Map()         {            string[,] MapArray = new string[xMaxArray, yMaxArray];        }        public void InsterItem(string Item, byte X, byte Y)        {            MapArray.SetValue(Item, Y, X);        }        public string ReadItem(byte X, byte Y)        {            MapArray.GetValue(X, Y);        }    }        static void Main(string[] args)        {            MapEngine Map1 = new MapEngine();            Map1.Map();

But do i access the new maparray referring to it as map1 or MapArray?

[Edited by - alvarofrank on July 11, 2007 3:52:06 PM]

Mike.Popoloski

3,259

July 11, 2007 03:30 PM

Quote: Original post by alvarofrank
i have a hard time understanding the difference between Starting an array like this:

Array names = Array.CreateInstance( typeof(String), 2, 4, 4 );

and like this:

string[,] names = new string[4, 4];

i want to use it to insert items in the array:

class MapEngine
{
private byte xMaxArray = 40;
private byte yMaxArray = 40;

public byte ModxMaxArray
{
get { return xMaxArray; }
set { xMaxArray = value; }
}

public byte ModyMaxArray
{
get { return yMaxArray; }
set { yMaxArray = value; }
}

public void Map()
{
string[,] MapArray = new string[xMaxArray, yMaxArray];
}

public void InsterItem(string Item, byte X, byte Y)
{
MapArray.SetValue(Item, Y, X);
}
public string ReadItem(byte X, byte Y)
{
MapArray.GetValue(X, Y);
}

}

static void Main(string[] args)
{
MapEngine Map1 = new MapEngine();
Map1.Map();

But do i access the new maparray referring to it as map1 or MapArray?

First of all, use the [ source lang="C#" ] and [ /source ] tags to display your source code, so that it gets a nice scrollbox, syntax highlighting, and correct formatting. Now, on to the question.

As you may have noticed, you cannot access your MapArray variable because it is a local variable, and gets thrown away once you leave the Map() function. InsertItem and ReadItem won't be able to find the variable because it won't exist after the Map() function is done running.

To access the elements of an array, you use the index operator, like this:

string[] array1;int[,] array2;string firstElement = array1[0];int firstInt = array2[0];array1[5] = "Hello";array2[3] = 54;

Mike Popoloski | Journal | SlimDX

paulecoyote

1,065

July 12, 2007 05:20 AM

Quote: Original post by JWalsh
Several people have pointed out how difficult it is to sort through 300+ posts in a single thread to determine if a question you asked has been answered, or worse, if your question has already been asked by someone else and THEN answered. To remedy this problem Superpig is currently researching a way to give the Workshop its own area here on GDNet, allowing for sub-forums, etc...This would enable us to have multiple threads per week, within a sub-forum designated for that week.

A QA forum for the workshop would do, or just keeping the lessons stickied and using this one. People could then post questions like this maybe:

[Week 1] What's the difference between a ref parameter and normal parameters?

And then if a thread has answers, one could assume that the query has been answered. Plus I guess it would make it easy to search for questions already asked.

I suppose that would quickly balloon though.

Anything posted is personal opinion which does not in anyway reflect or represent my employer. Any code and opinion is expressed “as is” and used at your own risk – it does not constitute a legal relationship of any kind.

Mike.Popoloski

3,259

July 12, 2007 07:53 AM

When this workshop first started, I assumed that having this nice C# Workshop forum at the top of the list would let people post different topics depending on the questions they were having, and then others could answer them, or see if their question was already posted somewhere else. Why isn't posting allowed in this forum?

Mike Popoloski | Journal | SlimDX

Knuckler

144

July 12, 2007 11:14 AM

JWalsh posted a example of expressions using components of RPGs. I wanted to see if I could expand on that. Despite programming in C++ on and off for seven years, this is the first time I've ever done anything related to "game programming." It's a very very very (I can't stress "very" enough) basic battle system. It actually could have ended up nicer. I wanted to use events to handle when a player was K.Oed. But it was 2:00 a.m in the morning, and I wanted it finished "now," so I took the easy way out. Just sharing it with ya'll:

using System;// A simple class to hold data for a hero or enemypublic class Character{    // Sets various attributes    public Character(int level, int hp, int strength, int armor)    {        this.level = level;        this.hp = hp;        this.strength = strength;        this.armor = armor;        this.koed = false;    }    public Character(): this(5, 40, 8, 7){}    public void SetStance(int val) { this.stance = val; }    public void Attack(Character enemy)    {        int modifier;        switch (this.stance)        {            case 1:                {                    this.armor += 3;                    this.strength -= 3;                } break;            case 2:                {                    this.armor -= 3;                    this.strength += 3;                } break;            default:                {                } break;        }        int damage = (this.level + this.strength) - enemy.Armor;        if (damage <= 0)            damage = 1;        enemy.Hp -= damage;        if(enemy.Hp <= 0)            enemy.KOED = true;        switch (this.stance)        {            case 1:                {                    this.armor -= 3;                    this.strength += 3;                    SetStance(0);                } break;            case 2:                {                    this.armor += 3;                    this.strength -= 3;                    SetStance(0);                } break;            default: { } break;        }    }    public int Level    {        get        {            return level;        }        set        {            level = value;        }    }    public int Hp    {        get        {            return hp;        }        set        {            hp = value;        }    }    public int Armor    {        get        {            return armor;        }        set        {            armor = value;        }    }    public int Strength    {        get        {            return strength;        }        set        {            strength = value;        }    }    public bool KOED    {        get        {            return koed;        }        set        {            koed = value;        }    }    public int Stance    {        get        {            return stance;        }    }    protected int level;            // The level of the entity    protected int hp;               // The current hitpoints of the character    protected int strength;         // The character's attack rating    protected int armor;            // The defense of the character    protected bool koed;            // If the character has 0 or less hp, this should be true    protected int stance;           // The stance of the character. 1 = defensive stance                                    // 2 = berserk stance}class Game{    public void ProcessAI(Character ai, Character enemy, Random rand)    {        if ((rand.Next() % 2) == 1)             // We attack the hero        {            ai.Attack(enemy);        }        else                             // We set our stance        {            if (ai.Stance != 0)            {                Console.WriteLine("Stance has already been set. Turn forfeited.");            }            else            {                ai.SetStance(rand.Next(1, 2));            }        }    }    public void ProcessPlayer(Character you, Character ai)    {        Console.WriteLine("What do you want to do? You can ATK or DEF.");        int maxturns = 3;        string command = null;        for(int i = 0; i < maxturns; i++)        {            command = Console.ReadLine();            if(command.ToUpper() == "ATK")            {                you.Attack(ai);                return;            }            if(command.ToUpper() == "DEF")            {                if(you.Stance != 0)                {                    Console.WriteLine("Stance has already been set.");                    break;                }                you.SetStance(1);                return;            }            Console.WriteLine("{0} chances left", maxturns - (i + 1));        }                Console.WriteLine("Turn forfeited.");    }    public void StatusReport(Character ai, Character player)    {        Console.WriteLine("You now have {0} HP. The enemy has {1} HP.", player.Hp, ai.Hp);    }    public void EnterGameMode(Character ai, Character player)    {        Console.WriteLine("==========================================================");        Console.WriteLine("Welcome to SimpleRPGExample");        Console.WriteLine("==========================================================");        Random rand = new Random();        Character monster = ai;        Character hero = player;        for (int i = 0; i < 4; i++)            Console.WriteLine();        Console.WriteLine("Get ready! The computer goes first!");        while (true)        {            ProcessAI(monster, hero, rand);            StatusReport(ai, hero);            if (hero.KOED)            {                Console.WriteLine("You were defeated.");                break;            }            ProcessPlayer(hero, monster);            StatusReport(ai, hero);            if (ai.KOED)            {                Console.WriteLine("You were victorious.");                break;            }        }        Console.WriteLine("Thanks for playing! GAME OVER!");    }}class RPG{    static void Main()    {        Character player = new Character();        Character monster = new Character();        Game game = new Game();        game.EnterGameMode(monster, player);    }}

Washu

7,836

July 12, 2007 11:33 AM

Quote: Original post by Knuckler
JWalsh posted a example of expressions using components of RPGs. I wanted to see if I could expand on that. Despite programming in C++ on and off for seven years, this is the first time I've ever done anything related to "game programming." It's a very very very (I can't stress "very" enough) basic battle system. It actually could have ended up nicer. I wanted to use events to handle when a player was K.Oed. But it was 2:00 a.m in the morning, and I wanted it finished "now," so I took the easy way out. Just sharing it with ya'll:

*** Source Snippet Removed ***

Magic numbers bad, mkay?
The first thing that popped out at me was this switch...with these funny magic numbers. Stance = 2? Huh? What the hell is stance, and what the hell does 2 have to do with it. Use enumerations. Secondly, you expose a stance property with just get, and then proceed to define a function to SET the stance. Use the set ability of properties. You also have this boolean for being KOED, but the condition for that is simply hp <= 0 (and the naming violates the recommended naming scheme by MS btw), so you can eliminate that boolean entirely.

I could go on, but I won't. One of the biggest problems with "finished now" things is that they tend to end up in even worse shape later on. Those quick hacks that you do today will remain tomorrow, and you'll compound upon them later by trying to do things quickly.

In time the project grows, the ignorance of its devs it shows, with many a convoluted function, it plunges into deep compunction, the price of failure is high, Washu's mirth is nigh.

Mike.Popoloski

3,259

July 12, 2007 12:26 PM

Yes.

Mike Popoloski | Journal | SlimDX

JWalsh

Author

498

July 12, 2007 12:58 PM

Quote: Original post by Mike.Popoloski
When this workshop first started, I assumed that having this nice C# Workshop forum at the top of the list would let people post different topics depending on the questions they were having, and then others could answer them, or see if their question was already posted somewhere else. Why isn't posting allowed in this forum?

Hi Mike,

The problem with just putting a forum up for everyone to post threads, is there's no sense of organization. People would be unable to determine what week the thread necessarily went with, or what difficulty level the question is.

The workshop is designed to coincide with the text, so anyone who has a question on the specification can easily locate the designated thread designed for posting questions on the related subject matter here in the workshop. Also, the idea is that if one person has a question, then it's likely that several people will have the same question. It works best if people follow the chapter threads closely.

People are currently unable to post threads in the workshop, because the intention is there is 1 thread per week, and then 1 thread per project. This nicely divides conversation based on the related chapters.

However, this is a learning process. The C# Workshop was based upon the C++ workshop which was formatted the same way. Unfortunately, or fortunately - depending on how you look at it, while the C++ Workshop got on average 35-50 posts per week, with week 1 and project 1 getting over 150 posts, the C# workshop has gotten over 300 posts in the first WEEK!

It's obvious that we're sinking under our own success. As I mentioned above, Superpig is looking at making a hybrid solution. The workshop is still broken up into nicely organized weeks and projects, but instead of it being 1 THREAD per week, it will be FORUM per week. This would allow people to post as many threads as they like within each of individual weeks. In essence, it provides the organization necessary for a sequential workshop, while also allowing people to freely create threads for easy reference.

I will speak with Superpig again to see how progress is going. Either way I will be posting the Week 2 thread within the next few days. I'm not sure when, exactly, because I will be out of town Friday afternoon to Tuesday night. I may post the thread before I leave, or via my laptop while out of town.

Cheers!

Jeromy Walsh
Sr. Tools & Engine Programmer | Software Engineer
Microsoft Windows Phone Team
Chronicles of Elyria (An In-development MMORPG)
GameDevelopedia.com - Blog & Tutorials
GDNet Mentoring: XNA Workshop | C# Workshop | C++ Workshop
"The question is not how far, the question is do you possess the constitution, the depth of faith, to go as far as is needed?" - Il Duche, Boondock Saints

Knuckler

144

July 12, 2007 01:24 PM

Quote: Original post by Washu
Quote: Original post by Knuckler
JWalsh posted a example of expressions using components of RPGs. I wanted to see if I could expand on that. Despite programming in C++ on and off for seven years, this is the first time I've ever done anything related to "game programming." It's a very very very (I can't stress "very" enough) basic battle system. It actually could have ended up nicer. I wanted to use events to handle when a player was K.Oed. But it was 2:00 a.m in the morning, and I wanted it finished "now," so I took the easy way out. Just sharing it with ya'll:

*** Source Snippet Removed ***

Magic numbers bad, mkay?
The first thing that popped out at me was this switch...with these funny magic numbers. Stance = 2? Huh? What the hell is stance, and what the hell does 2 have to do with it. Use enumerations. Secondly, you expose a stance property with just get, and then proceed to define a function to SET the stance. Use the set ability of properties. You also have this boolean for being KOED, but the condition for that is simply hp <= 0 (and the naming violates the recommended naming scheme by MS btw), so you can eliminate that boolean entirely.

I could go on, but I won't. One of the biggest problems with "finished now" things is that they tend to end up in even worse shape later on. Those quick hacks that you do today will remain tomorrow, and you'll compound upon them later by trying to do things quickly.

The stance field represents the mode of combat a character can be in. 0 is neutral stance. 1 is defensive stance (take and deal less damage). 2 is berserker stance (take and deal more damage). An enum is a better choice for representing the types of stances. I see that "NOW." It's a feature of C++ I never used extensively. For me it's just not as obvious to use such a feature compared to a more seasoned programmer. Especially at 2 in the morning.

Thanks you for your advice, Washu. The code could have came out a bit nicer if I was in a clearer state of mind. I'm going to rewrite it for myself to see if it can come out better. I'm definitely going to take your advice about "finished now" projects to heart for future programs.

alvarofrank

122

July 12, 2007 03:30 PM

I keep trying to use arrays but i cant seem to get 1 to work. I cant initialie and refer to it.
Here is what i got:

    class MapEngine    {        private byte xMaxArray = 40;        private byte yMaxArray = 40;        static string[,] MapArray;        public byte ModxMaxArray        {            get { return xMaxArray; }            set { xMaxArray = value; }        }        public byte ModyMaxArray        {            get { return yMaxArray; }            set { yMaxArray = value; }        }                public void InsterItem(string Item, byte X, byte Y)        {            MapArray.SetValue(Item, X, Y);        }        public string ReadItem(byte X, byte Y)        {            return MapArray.GetValue(X, Y);        }    }    class Unit    {        private string ID;        private string Type;        private string Status;        private int pHealth;        private int pAttack;        private int pDefense;        private int pCharge;        private int pMorale;        private int Range;        private int Speed;        private byte Posx;        private byte Posy;        private int Angle;        public void Die()        {            pHealth = 0;            Status = "Dead";            MapArray.InsertItem("Empty", Posx, Posy);        }        public void Move(string Where, int Heading)        {            Angle = Heading;            switch (Where)            {                case "Forward":                    if (MapArray.ReadItem(Posx, (Posy + 1)) = "Empty")                    {                        if (Posx != 60)                        {                            MapArray.InsertItem("Empty", Posx, Posy);                            Posy += 1;                            MapArray.InsertItem(ID, Posx, Posy);                            Status = "Moving Forward!";                        }                        else Status = "We cant Advance Anymore!";                    }                    else Status = "We can't advance, the enemy is holding that position!";                    break;            }        }   }

I get the following errors:
The name 'MapArray' does not exist in the current context.
I am having a hard time understanding how to Create, Construct, use, refer, set and get values from an array.

C# Workshop - Week 1 (Ch. 1 & 2) - Advanced

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