1301 Review Part 2

More Stuff You Should Know

Briana B. MorrisonCSE 1302C

Spring 2010

2CSE 1302C

Topics• Defining classes

• Using objects

3CSE 1302C

Defining a Class• Contain members

– Attributes (data)• Instance• Class (static)

– Methods (behaviors)• Instance• Class (static)

• Access (public, protected, private)

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Trophy Example• Define a class that would store the

trophy name and points

• Attributes

• What methods– Constructor– Properties (accessors / mutators)– Ability to print (overload ToString)

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class Trophy {

// attributes private string _Name; private int _Points = 10;

// default constructor public Trophy()

{ _Name = "Yeah that's a problem"; _Points = 0; }

// overloaded constructor public Trophy (string n, int p) { _Name = n; Points = p; }}

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class Trophy { // properties public string Name { get { return _Name; } }

public int Points { get { return _Points; } set { if (value > 0) _Points = value; } }}

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class Trophy

{

// overloaded ToString

public override string ToString()

{

return _Name + " (" + _Points + ")";

}

}

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Using a Class• Declare and instantiate an instance

• Print the values of the instance

• Create a collection (array) of trophy instances

• Read in values, sum the points in the collection

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// declare and instantiate instance

Trophy t = new Trophy("100 kills", 10);

// print values

Console.WriteLine(t);

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// create collectionTrophy[ ] data_storage;Console.Write("How many trophies: ");int trophie_count;trophie_count = Int32.Parse(Console.ReadLine());data_storage = new Trophy[trophie_count];

// read in valuesstring name;int points;for (int i = 0; i < trophie_count; i++){ Console.Write("Enter trophy " + i + " name:"); name = Console.ReadLine(); Console.Write("Enter points for this trophy: "); points = Int32.Parse(Console.ReadLine()); data_storage[i] = new Trophy(name, points);}

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// print collection and total pointsint sum = 0;Console.WriteLine("Uber Gamer Prophile");// for (int i = 0; i < data_storage.Length; i++)// Console.WriteLine(data_storage[i]);// data_storage[0].Points += 9;foreach (Trophy troph in data_storage) Console.WriteLine(troph);foreach (Trophy troph in data_storage) sum += troph.Points;Console.WriteLine("Your points are " + sum);

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Another Class Example• How about a superhero class

– Name– Superhero ability

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class Hero { public enum PowerType {Strength, Fly, Speed, MindControl, SprVision}; public string Name; public PowerType SuperPower;

}

Notice in the above that the enum allows us to define a new "type", but this is actually just a place holder for integers.

14CSE 1302C

class Hero {

public void Fight(Hero opponent) { if (this.SuperPower == PowerType.SprVision) { Console.WriteLine(this.Name + " beats up " + opponent.Name); } else { Console.WriteLine(Name + " fights " + opponent.Name); } } }

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Use the Hero Class• Create 2 heroes with powers and have

them fight.

•

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class Program { static void Main(string[ ] args) { Hero SpiderMan; SpiderMan = new Hero(); SpiderMan.Name = "Peter Parker"; SpiderMan.SuperPower = Hero.PowerType.BusVision;

Hero Venom = new Hero();// Hero Venom;// Venom = null; Venom.Name = "Venom"; Venom.SuperPower = Hero.PowerType.Fly;

Venom.Fight(SpiderMan); SpiderMan.Fight(Venom); Console.Write("Press ENTER"); Console.ReadLine(); } }

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class Program { static void Main(string[] args) { DoArrayStuff(); }

// ------------------------------------------------------- private static void DoArrayStuff() { int[ ] nums = new int[10]; //remember to not forget to use "new" to allocate memory for your object.

for (int i = 0; i < 10; i++) { Console.Write("Enter number " + i + " : "); nums[i] = Int32.Parse(Console.ReadLine()); }

float average = FindAverage(nums);

Console.WriteLine("The average is " + average);

int min = FindMin(nums); Console.WriteLine("The min is " + min); }

}

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private static int FindMin(int[] A) { int temp = A[0];

for (int i = 1; i < 10; i++) { if (temp > A[i]) temp = A[i]; }

return temp; }

// ------------------------------------------------------- private static float FindAverage(int[] A) { int sum = 0;

for (int i = 0; i < 10; i++) { sum += A[i]; }

return sum / 10f; }

Also note that the parameters (in this case "nums") when you invoke a method can be called something in the method itself (in this case "A"). Parameters match in position and type, so the name doesn't matter.

19CSE 1302C

Questions?