Basic List Practice

Complete the following exercises related to List objects.

Exercise 1: Bugs

Visit each of the following Repls. Start by trying to run the programs, and make a note of any error messages received. Then, fork the Repl and try to fix the code!

• Bug 1
• Bug 2
• Bug 3
• Bug 4
• Bug 5

Exercise 2: A Playlist of Your Favorite Songs

Think of some of your favorite songs. Create a program that adds those songs to a list, and then displays them!

1. Create a new project in Repl
2. At the top of the file, add using System.Collections.Generic;
3. In the body of the Main method, print out a message that says "My Favorite Songs"
4. Under that, initialize a new List<string> object named songs

    List<string> songs = new List<string>();
   

5. Under that, add a few of your favorite songs to the list

    songs.Add("9 to 5 by Dolly Parton");
    // etc
   

6. Under that, create a foreach loop to loop through each string in the songs list

    foreach (string song in songs) { }
   

7. In the body of the foreach loop, print out the song

    Console.WriteLine(song);
   

Run the program, and make sure that all the songs in the list appear!

Exercise 3: Spaced Out Text

Sometimes, people on the internet like to display messages with extra spaces between each text character. For example, instead of writing THE VOID, they might write T H E V O I D. Create a program that allows the user to input some text, and gives them the "spaced" version of that text!

Background - string Objects

For this to work, it is important to know that a string object can actually be treated as a List of char objects. A char is just like a string, only it contains one single character instead of multiple characters. This means that, given a string variable named myString it is possible to do something like this:

foreach (char c in myString)
{
    Console.WriteLine(c);
}

The code above would print out each individual character in the string!

Implementation

Follow the steps below to implement the "Spaced Out Text" program.

1. Create a new project in Repl
2. In the body of the Main method, print out a message that says "Enter some text to space out"
3. Under that, create a new string variable named text
4. Set the text variable to the result of Console.ReadLine()
5. Under that, create another string variable named spacedText
   • This will hold the "spaced out" text
6. Set the spacedText variable to be an empty string ("")
7. Under that, create a foreach loop that will loop through each char c in the text string

    foreach (char c in text) { }
   

8. In the body of the foreach loop, add c and an extra space to the spacedText variable

    spacedText += c + " ";
   

9. Under the foreach loop, print out the final spacedText value

Run the program. Make sure it is possible to enter some text, and see the spaced out version of it!

Exercise 4: Course Ranking

Think about all of the courses you take in school. Order them by how much you like them, with number 1 being the top course. Create a program that will allow the user to check which course corresponds with each ranking.

1. Create a new project in Repl
2. At the top of the file, add using System.Collections.Generic;
3. In the body of the Main method, print out a message that says "Course Ranking"
4. Under that, initialize a new List<string> object named courses

    List<string> courses = new List<string>();
   

5. Under that, add each of your courses in order, with the top course coming first

    courses.Add("Geometry");
    // etc
   

6. Under that, use Console.WriteLine to ask the user which ranking they would like to see
7. Under that, create a new int variable named rank
8. Set the rank variable to Convert.ToInt32(Console.ReadLine())
9. Under that, create a new int variable named rankIndex, and set it to rank - 1
   • Note that this is necessary because List objects start index at 0
10. On the next line, create a new string variable named courseAtRank
11. Set the courseAtRank variable to the element of the list at the rankIndex index

     string courseAtRank = courses[rankIndex];
    

12. On the next line, print out the value of the courseAtRank variable

Run the program and verify that the proper courses appear based on what the user enters!

Bonus - Limited Ranking

Currently, if the user enters something outside of the range of the course ranking list, the program will fail. Update it so that it checks whether the rank the user enters is within range. If it is not, display a message saying "Course Ranking Not In Range."