rules

Rules

• Two Teams• Questions worth 1-3 points

– Entire team can confer to answer the question– Max of 2 minutes per question– You can use a computer on any question except “what does this

program output…”• Teams switch when either

– Three questions have been asked or– A team answers incorrectly three times (three strikes)

• After three strikes, the opposing team can “steal” the points by answering the question correctly

• Team with the most points at the end wins

Question 1 of 12• Name at least two ways a List is more flexible

than an array.

Answer 1 (2 points)• Name at least two ways a List is more flexible

than an array.– Don’t have to specify the size of the List, can add

items to the end– Can remove items at a specified index– Built-in methods to search the list

Question 2 (3 points)• What is the output of this code?

int[] a = { 0, 1, 1, 0, 2, 1 }; int[] h = new int[3]; h[0] = 0; h[1] = 0; h[2] = 0; for (int i = 0; i < a.Length; i++) { h[a[i]]++; } Console.WriteLine(h[0]); Console.WriteLine(h[1]); Console.WriteLine(h[2]);

Answer 2• 2• 3• 1

Question 3 (1 point)• If a method is declared to be virtual then what

can we do with that method in a derived class?

Answer 3• Override it

Question 4 (1 point)• Write code that creates an instance of the

Dude class using the constructor (send in any data you like that is valid)

class Dude { private string name; private int age; public Dude(string n, int a) { name = n; age = a; } }

Answer 4• Dude dude = new Dude("Ben Curtis", 29);

Question 5 (3 point)• Write equivalent code that uses two while

loops instead of two for loops

for (int i = 0; i < 10; i++) { for (int j = 0; j < i; j++) { int temp = ary[j]; ary[j] = ary[i]; ary[i] = temp; } }

Answer 5• Code int i = 0;

while (i < 10) { int j = 0; while (j < i) { int temp = ary[j]; ary[j] = ary[i]; ary[i] = temp; j++; } i++; }

Question 6 (2 points)• What is the difference between a reference

type and a primitive type?

Answer 6• Primitive type stores the actual value directly

in the memory location for the variable• Reference type stores an address in memory,

or a reference, to another place in memory that stores the actual value of the data

Question 7 (2 points)• Give the code to create a variable named

“nums” that is a List of doubles, and then add 3.5 and 10.4 to the list

Answer 7• List<double> nums = new List<double>();• nums.Items.Add(3.5);• nums.Items.Add(10.4);

Question 8 (1 point)• What is the difference between public,

private, and protected?

Answer 8• Public: accessible from outside the class• Private: accessible only inside the class• Protected: accessible inside the class and in

any derived classes

Question 9 (3 points)• Write a class named “AfricanGrey” that is

derived from Parrot and override description() to return “Grey with red tails”

class Parrot { public virtual string description() { return ("Talking Bird"); } }

Answer 9• Code

class AfricanGrey : Parrot { public override string description() { return ("Grey with Red Tails"); } }

Question 10 (1 point)• How is it that inheritance helps us eliminate

redundant code?

Answer 10• Methods or variables can be defined in parent

classes and are “inherited” by any derived class, so we don’t have to write the inherited code again

Question 11 (2 points)• Fill in the blanks so the method accepts an

array of strings and a target string, and also invokes the method

public bool search( __________ ary, string targetname){ for (int i = 0; i < ary.Length; i++) { if (ary[i].Equals(targetname)) return true; } return false;}

public void button_click(){ string[] ary = { "Joe", "Bob", "Ted" }; if (search( _______ , "Ted")) { MessageBox.Show ("Ted is in the array."); }}

Answer 11• Code

public bool search( string[] ary, string targetname){ for (int i = 0; i < ary.Length; i++) { if (ary[i].Equals(targetname)) return true; } return false;}

public void button_click(){ string[] ary = { "Joe", "Bob", "Ted" };

if (search( ary , "Ted")) { MessageBox.Show ("Ted is in the array."); }}

Question 12 (3 points)• Give the output

private void question12(string[] a, int count) { a[2] = ""; count--; }private void button6_Click(object sender, EventArgs e){ string[] ary = { "Joe", "Bob", "Ted" }; int count = 3;

question12(ary, count); Console.WriteLine("Count: " + count); for (int i = 0; i < count; i++) { Console.WriteLine(ary[i]); }}

Answer 12• Count = 3• Joe• Bob• <blank>

The End

Runoff Question• Write the Money class so the following code

works:

Money dinero = new Money(10000, "pesos");Money cash = new Money(5, "dollars");

// Outputs 10000 pesosMessageBox.Show(dinero.Amount + " " + dinero.Currency);// Outputs 5 dollarsMessageBox.Show(cash.Amount + " " + cash.Currency);

Answer class Money { private int amount; public int Amount { get { return amount; } set { amount = value; } } private string currency; public string Currency { get { return currency; } set { currency = value; } } public Money(int a, string c) { amount = a; currency = c; } }