
- •Microsoft C# Programming for the Absolute Beginner
- •Table of Contents
- •Microsoft C# Programming for the Absolute Beginner
- •Introduction
- •Overview
- •Chapter 1: Basic Input and Output: A Mini Adventure
- •Project: The Mini Adventure
- •Reviewing Basic C# Concepts
- •Namespaces
- •Classes
- •Methods
- •Statements
- •The Console Object
- •.NET Documentation
- •Getting into the Visual Studio .Net Environment
- •Examining the Default Code
- •Creating a Custom Namespace
- •Adding Summary Comments
- •Creating the Class
- •Moving from Code to a Program
- •Compiling Your Program
- •Looking for Bugs
- •Getting Input from the User
- •Creating a String Variable
- •Getting a Value with the Console.ReadLine() Method
- •Incorporating a Variable in Output
- •Combining String Values
- •Combining Strings with Concatenation
- •Adding a Tab Character
- •Using the Newline Sequence
- •Displaying a Backslash
- •Displaying Quotation Marks
- •Launching the Mini Adventure
- •Planning the Story
- •Creating the Variables
- •Getting Values from the User
- •Writing the Output
- •Finishing the Program
- •Summary
- •Chapter 2: Branching and Operators: The Math Game
- •The Math Game
- •Using Numeric Variables
- •The Simple Math Game
- •Numeric Variable Types
- •Integer Variables
- •Long Integers
- •Data Type Problems
- •Math Operators
- •Converting Variables
- •Explicit Casting
- •The Convert Object
- •Creating a Branch in Program Logic
- •The Hi Bill Game
- •Condition Testing
- •The If Statement
- •The Else Clause
- •Multiple Conditions
- •Working with The Switch Statement
- •The Switch Demo Program
- •Examining How Switch Statements Work
- •Creating a Random Number
- •Introducing the Die Roller
- •Exploring the Random Object
- •Creating a Random Double with the .NextDouble() Method
- •Getting the Values of Dice
- •Creating the Math Game
- •Designing the Game
- •Creating the Variables
- •Managing Addition
- •Managing Subtraction
- •Managing Multiplication and Division
- •Checking the Answers
- •Waiting for the Carriage Return
- •Summary
- •Chapter 3: Loops and Strings: The Pig Latin Program
- •Project: The Pig Latin Program
- •Investigating The String Object
- •The String Mangler Program
- •A Closer Look at Strings
- •Using the Object Browser
- •Experimenting with String Methods
- •Performing Common String Manipulations
- •Using a For Loop
- •Examining The Bean Counter Program
- •Creating a Sentry Variable
- •Checking for an Upper Limit
- •Incrementing the Variable
- •Examining the Behavior of the For Loop
- •The Fancy Beans Program
- •Skipping Numbers
- •Counting Backwards
- •Using a Foreach Loop to Break Up a Sentence
- •Using a While Loop
- •The Magic Word Program
- •Writing an Effective While Loop
- •Planning Your Program with the STAIR Process
- •S: State the Problem
- •T: Tool Identification
- •A: Algorithm
- •I: Implementation
- •R: Refinement
- •Applying STAIR to the Pig Latin Program
- •Stating the Problem
- •Identifying the Tools
- •Creating the Algorithm
- •Implementing and Refining
- •Writing the Pig Latin Program
- •Setting Up the Variables
- •Creating the Outside Loop
- •Dividing the Phrase into Words
- •Extracting the First Character
- •Checking for a Vowel
- •Adding Debugging Code
- •Closing Up the code
- •Summary
- •Introducing the Critter Program
- •Creating Methods to Reuse Code
- •The Song Program
- •Building the Main() Method
- •Creating a Simple Method
- •Adding a Parameter
- •Returning a Value
- •Creating a Menu
- •Creating a Main Loop
- •Creating the Sentry Variable
- •Calling a Method
- •Working with the Results
- •Writing the showMenu() Method
- •Getting Input from the User
- •Handling Exceptions
- •Returning a Value
- •Creating a New Object with the CritterName Program
- •Creating the Basic Critter
- •Using Scope Modifiers
- •Using a Public Instance Variable
- •Creating an Instance of the Critter
- •Adding a Method
- •Creating the talk() Method for the CritterTalk Program
- •Changing the Menu to Use the talk() Method
- •Creating a Property in the CritterProp Program
- •Examining the Critter Prop Program
- •Creating the Critter with a Name Property
- •Using Properties as Filters
- •Making the Critter More Lifelike
- •Adding More Private Variables
- •Adding the Age() Method
- •Adding the Eat() Method
- •Adding the Play() Method
- •Modifying the Talk() Method
- •Making Changes in the Main Class
- •Summary
- •Introducing the Snowball Fight
- •Inheritance and Encapsulation
- •Creating a Constructor
- •Adding a Constructor to the Critter Class
- •Creating the CritViewer Class
- •Reviewing the Static Keyword
- •Calling a Constructor from the Main() Method
- •Working with Multiple Files
- •Overloading Constructors
- •Viewing the Improved Critter Class
- •Adding Polymorphism to Your Objects
- •Modifying the Critter Viewer in CritOver to Demonstrate Overloaded Constructors
- •Using Inheritance to Make New Classes
- •Creating a Class to View the Clone
- •Creating the Critter Class
- •Improving an Existing Class
- •Introducing the Glitter Critter
- •Adding Methods to a New Class
- •Changing the Critter Viewer Again
- •Creating the Snowball Fight
- •Building the Fighter
- •Building the Robot Fighter
- •Creating the Main Menu Class
- •Summary
- •Overview
- •Introducing the Visual Critter
- •Thinking Like a GUI Programmer
- •Creating a Graphical User Interface (GUI)
- •Examining the Code of a Windows Program
- •Adding New Namespaces
- •Creating the Form Object
- •Creating a Destructor
- •Creating the Components
- •Setting Component Properties
- •Setting Up the Form
- •Writing the Main() Method
- •Creating an Interactive Program
- •Responding to a Simple Event
- •Creating and Adding the Components
- •Adding an Event to the Program
- •Creating an Event Handler
- •Allowing for Multiple Selections
- •Choosing a Font with Selection Controls
- •Creating the User Interface
- •Examining Selection Tools
- •Creating Instance Variables in the Font Chooser
- •Writing the AssignFont() Method
- •Writing the Event Handlers
- •Working with Images and Scroll Bars
- •Setting Up the Picture Box
- •Adding a Scroll Bar
- •Revisiting the Visual Critter
- •Designing the Program
- •Determining the Necessary Tools
- •Designing the Form
- •Writing the Code
- •Summary
- •Chapter 7: Timers and Animation: The Lunar Lander
- •Introducing the Lunar Lander
- •Reading Values from the Keyboard
- •Introducing the Key Reader Program
- •Setting Up the Key Reader Program
- •Coding the KeyPress Event
- •Coding the KeyDown Event
- •Determining Which Key Was Pressed
- •Animating Images
- •Introducing the ImageList Control
- •Setting Up an Image List
- •Looking at the Image Collection
- •Displaying an Image from the Image List
- •Using a Timer to Automate Animation
- •Introducing the Timer Control
- •Configuring the Timer
- •Adding Motion
- •Checking for Keyboard Input
- •Working with the Location Property
- •Detecting Collisions between Objects
- •Coding the Crasher Program
- •Getting Values for newX and newY
- •Bouncing the Ball off the Sides
- •Checking for Collisions
- •Extracting a Rectangle from a Component
- •Getting More from the MessageBox Object
- •Introducing the MsgDemo Program
- •Retrieving Values from the MessageBox
- •Coding the Lunar Lander
- •The Visual Design
- •The Constructor
- •The timer1_Tick() Method
- •The moveShip() Method
- •The checkLanding() Method
- •The theForm_KeyDown() Method
- •The showStats() Method
- •The killShip() Method
- •The initGame() Method
- •Summary
- •Chapter 8: Arrays: The Soccer Game
- •The Soccer Game
- •Introducing Arrays
- •Exploring the Counter Program
- •Creating an Array of Strings
- •Referring to Elements in an Array
- •Working with Arrays
- •Using the Array Demo Program to Explore Arrays
- •Building the Languages Array
- •Sorting the Array
- •Designing the Soccer Game
- •Solving a Subset of the Problem
- •Adding Percentages for the Other Players
- •Setting Up the Shot Demo Program
- •Setting Up the List Boxes
- •Using a Custom Event Handler
- •Writing the changeStatus() Method
- •Kicking the Ball
- •Designing Programs by Hand
- •Examining the Form by Hand Program
- •Adding Components in the Constructor
- •Responding to the Button Event
- •Building the Soccer Program
- •Setting Up the Variables
- •Examining the Constructor
- •Setting Up the Players
- •Setting Up the Opponents
- •Setting Up the Goalies
- •Responding to Player Clicks
- •Handling Good Shots
- •Handling Bad Shots
- •Setting a New Current Player
- •Handling the Passage of Time
- •Updating the Score
- •Summary
- •Chapter 9: File Handling: The Adventure Kit
- •Introducing the Adventure Kit
- •Viewing the Main Screen
- •Loading an Adventure
- •Playing an Adventure
- •Creating an Adventure
- •Reading and Writing Text Files
- •Exploring the File IO Program
- •Importing the IO Namespace
- •Writing to a Stream
- •Reading from a Stream
- •Creating Menus
- •Exploring the Menu Demo Program
- •Adding a MainMenu Object
- •Adding a Submenu
- •Setting Up the Properties of Menu Items
- •Writing Event Code for Menus
- •Using Dialog Boxes to Enhance Your Programs
- •Exploring the Dialog Demo Program
- •Adding Standard Dialogs to Your Form
- •Using the File Dialog Controls
- •Responding to File Dialog Events
- •Using the Font Dialog Control
- •Using the Color Dialog Control
- •Storing Entire Objects with Serialization
- •Exploring the Serialization Demo Program
- •Creating the Contact Class
- •Referencing the Serializable Namespace
- •Storing a Class
- •Retrieving a Class
- •Returning to the Adventure Kit Program
- •Examining the Room Class
- •Creating the Dungeon Class
- •Writing the Game Class
- •Writing the Editor Class
- •Writing the MainForm Class
- •Summary
- •Chapter 10: Chapter Basic XML: The Quiz Maker
- •Introducing the Quiz Maker Game
- •Taking a Quiz
- •Creating and Editing Quizzes
- •Investigating XML
- •Defining XML
- •Creating an XML Document in .NET
- •Creating an XML Schema for Your Language
- •Investigating the .NET View of XML
- •Exploring the XmlNode Class
- •Exploring the XmlDocument Class
- •Reading an Existing XML Document
- •Creating the XML Viewer Program
- •Writing New Values to an XML Document
- •Building the Document Structure
- •Adding an Element to the Document
- •Displaying the XML Code
- •Examining the Quizzer Program
- •Building the Main Form
- •Writing the Quiz Form
- •Writing the Editor Form
- •Summary
- •Overview
- •Introducing the SpyMaster Program
- •Creating a Simple Database
- •Accessing the Data Server
- •Accessing the Data in a Program
- •Using Queries to Modify Data Results
- •Limiting Data with the SELECT Statement
- •Using an Existing Database
- •Adding the Capability to Display Queries
- •Creating a Visual Query Builder
- •Working with Relational Databases
- •Improving Your Data with Normalization
- •Using a Join to Connect Two Tables
- •Creating a View
- •Referring to a View in a Program
- •Incorporating the Agent Specialty Attribute
- •Working with Other Databases
- •Creating a New Connection
- •Converting a Data Set to XML
- •Reading from XML to a Data Source
- •Creating the SpyMaster Database
- •Building the Main Form
- •Editing the Assignments
- •Editing the Specialties
- •Viewing the Agents
- •Editing the Agent Data
- •Summary
- •List of Figures
- •List of Tables
- •List of Sidebars
having the ball,
//all others not having the ball
//set up the current player variable currentPlayer = playerNumber;
//show no player with ball for(int i = 0; i < 5; i++){
picPlayer[i].BorderStyle = BorderStyle.None; picPlayer[i].Image = myPics.Images[2];
} // end for loop
//reset goalie image picPlayer[GOALIE].Image = myPics.Images[5];
//show current player holding ball picPlayer[playerNumber].BorderStyle =
BorderStyle.FixedSingle; picPlayer[playerNumber].Image = myPics.Images[3];
}// end setPlayer
Before I set up the visual representation of the player with the ball, I ensure that the preceding player is shown without the ball. The easiest way to do this is to set all the players without the ball. A player without the ball is represented by image 2 of the image list and has no border. The goalie image (if he doesn’t have the ball) is image 5 of the image list. When all the images are clear, I set the border style of the current player to a fixed single−line border, and I set the image to image 3 of the image list, which shows the player with the ball.
Trick At first, I just used the ball to indicate which player had the ball, but the ball is so tiny that it is hard to spot. I added the border as an easy way to determine which player currently has the ball. Many sports games do something similar to ease gameplay.
Handling the Passage of Time
The program has a timer control used to pace the game. When the timer ticks, three things happen. The clock is updated, showing how many seconds are left of playing time. The player picture boxes are moved randomly, and the opponent picture boxes are also moved randomly. It shouldn’t surprise you that each of these three tasks is relegated to a method, the updateTime(), movePlayers(), and moveOpp() methods.
private void timer1_Tick(object sender, System.EventArgs e) {
updateTime();
movePlayers();
moveOpp();
} // end timerTick
Again, encapsulation comes to the rescue. The timer_tick() method calls three other methods to do all the work, but it’s easy to see from the tick method exactly which tasks occur whenever the timer ticks.
Updating the Clock
The first task is to update the clock. This seems quite simple, and it is, but merely reporting how much time is left is not enough. At some point, the user will be out of time, and the game will have to
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end. The code to handle the end of the game is called inside the updateTime() method:
private void updateTime(){ //calculate time left timeLeft−−;
if (timeLeft <=0){ timer1.Enabled = false;
DialogResult playAgain = MessageBox.Show ("Game Over. Play Again?", "Soccer",
MessageBoxButtons.YesNo);
if (playAgain == DialogResult.Yes){ //start over
playerScore = 0; oppScore = 0; timeLeft = 600;
currentPlayer = FULLBACK; updateScore(); timer1.Enabled = true;
}else {
// end game Application.Exit();
}// end playAgain if
}else {
double totalSeconds = timeLeft/10;
int minutes = (int) (totalSeconds /60); int seconds = (int) (totalSeconds % 60);
string timeString = minutes.ToString() + ":
"+ seconds.ToString();
lblTime.Text = timeString;
} // end if
}// end updateTime
The first order of business is to decrement the timeLeft variable. This variable started out at 600, and it will be decremented by 1 each time the timer ticks. Because the timer is set at an interval of 10 frames per second, timeLeft will be 0 after 60 seconds. If timeLeft is less than or equal to 0, time has expired. In this situation, I display a dialog box asking whether the user wants to play again. If so, I reset all the key variables (score, time left, and current player variables) and restart the timer. If not, I end the application.
If the value of timeLeft is larger than 0, I do some quick math to determine how many minutes and seconds are left and then send this value to the user.
Trick Notice how I use the % operator to determine the number of seconds. This is called the modulus operator. It comes in handy in a number of situations, but many people don’t know about it. The modulus operator returns the remainder of a long division problem. For example, if totalSeconds had the value 63, minutes would get the value 61 divided by 60, or 1 with a remainder of 3. If you divide two integers, the result is an integer, which completely ignores the remainder value. You can use the modulus operator to get the remainder of a division problem.
The minutes and seconds are stored as integers, so I reformatted them to send them to the time label.
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Moving the Players
Part of this game's appeal is the way the little players run around on the field. To be honest, the movement of the players has absolutely no effect on the outcome of the game as it is currently set up. However, the action does add appeal, and you could change the code so that the distance between a player and the goal is the major determinate of the likelihood the player will score. (Hmmm, sounds like another good exercise.) All player motion is entirely random, as you can see from the code:
private void movePlayers(){ //move players
int motion;
Random roller = new Random();
for (int i = 1; i < 5; i++){ motion = roller.Next(11) − 5; picPlayer[i].Left += motion; motion = roller.Next(11) −5; picPlayer[i].Top += motion;
//check for boundaries
if (picPlayer[i].Left < 0){ picPlayer[i].Left = 0;
}else if (picPlayer[i].Left + picPlayer[i].Width > pnlField.Width){
picPlayer[i].Left = pnlField.Width − picPlayer[i].Width;
}else if (picPlayer[i].Top < 0){ picPlayer[i].Top = 0;
}else if (picPlayer[i].Top + picPlayer[i].Height > pnlField.Height){
picPlayer[i].Top = pnlField.Height − picPlayer[i].Height;
}// end if
}// end for loop
}// end movePlayers
I set up a for loop to go one at a time through each player (except the goalies—they don’t move).
I used a random integer named motion to determine how much the player would move. I played with the motion variable to get exactly the effect I was looking for. The solution I settled on calls for grabbing a number between 0 and 10 and then subtracting 5 from that number. This results in a random value between –5 and 5.
Trap My first thought was to use the two−integer version of the random object’s Next() method to extract a value in the range I wanted. However, when I experimented with that approach, I found that the numbers were not as random as I wanted. They tended to be negative far more often than positive. This caused all my players to drift toward one corner of the field, which was not the behavior I was looking for. There’s a lesson here. You can try to find methods and objects that make your life easier, but you still have to test. If they don’t do what you want, you must figure out another way.
I added motion to the Left property of the player, recalculated motion using the same formula, and added it to the Top property. The net effect is that each element moves up to 5 pixels in each
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direction randomly each time the timer ticks, making the nice random motion of players on the screen.
As you’ve heard by now, whenever you increment or decrement a variable, you should check for boundary conditions. In this case, this means making sure that the players don’t move off the field. I did this by comparing the player’s position with the field panel.
Moving the Opponents
The motion of the opponents is very much like that of the players. In fact, all I did was copy the code and change the picture box name to picOpp.
Hint Usually, when you find yourself copying code, it’s an indicator that you should modify your data structure. I decided not to in this case because although the motion of the opponents and the players is identical, players and opponents are different in many other aspects, so they should still be different arrays.
private void moveOpp(){ //move opponents
int motion;
Random roller = new Random();
for (int i = 1; i < 5; i++){ motion = roller.Next(11) − 5; picOpp[i].Left += motion; motion = roller.Next(11) −5; picOpp[i].Top += motion;
//check for boundaries if (picOpp[i].Left < 0){
picOpp[i].Left = 0;
}else if (picOpp[i].Left + picOpp[i].Width > pnlField.Width){
picOpp[i].Left = pnlField.Width − picOpp[i].Width;
}else if (picOpp[i].Top < 0){ picOpp[i].Top = 0;
}else if (picOpp[i].Top + picOpp[i].Height > pnlField.Height){
picOpp[i].Top = pnlField.Height − picOpp[i].Height;
}// end if
}// end for loop
}// end moveOpp
As in the player movement scheme, the position of the opponents has no bearing on the game play. In fact, the opposing players are completely unnecessary. They are just there for visual effect.
Updating the Score
Updating the score is an easy chore, but because it’s done from several places, it is a good candidate for a method call:
private void updateScore(){ lblPlScore.Text = "Player: " +
playerScore.ToString(); lblOppScore.Text = " Opp: " +
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