Problem 1

For this first problem, you needed to remember that

• a declaration is the act of creating and naming a variable, a statement of the form int myAge;
• an assignment is the act of setting the value of a variable, a statement of the form myAqe = 12;
• an instantiation is the act of creating an object from a class (and assigning its value to a variable, actually, in our examples), a statement of the form Rectangle myRec = new Rectangle();
• an initialization is a declaration and an assignement combined in one statement, a statement of the form int myAge = 12;

I consider those to be extremely basic notions. Failing at this problem is unfortunately an extremely worisome sign…

Problem 2

This was about implicit and explicit conversion. Not an easy topic, but you had plenty of opportunities to practice and learn.

Problem 3

This exercise, about displaying various strings, had some tricky aspects. Note that, for instance, Console.WriteLine("myVar");, would simply display “myVar” followed by a a new line, and not the value possibly held by this variable. All of the pitfals could be detected with a carefull reading of the statements – something I like to encourage you to do.

Problem 4

Those exercises were extremely close to what you had in the homework. It was a way of making sure that you had practised those.

Problem 5

This one was difficult, as it asked you to write a small program from start to finish. Having successfully completed the project was the best way to get prepared for it.

decimal total = 0; // Variable used to hold the total due. 
Console.WriteLine ("How many glasses of lemonade would you like?");
total += decimal.Parse(Console.ReadLine()); // Lemonade is $1 a glass.
Console.WriteLine ("How many cookies would you like?");
total += decimal.Parse(Console.ReadLine()) * 1.5M; // Cookies are $1.5 each.
total *= 1.10M; // We add the taxes.
Console.WriteLine($"Your total is {total:C}."); // We display the total nicely, using the format specifier.

string name; // Variable to hold the user's name.
int ageInYears; // Variable to hold the user's age in years.
Console.WriteLine ("What is your name?");
name = Console.ReadLine(); // We read from the user their name.
Console.WriteLine ("What is your age?");
ageInYears = int.Parse(Console.ReadLine()); // We read and convert from the user their aqe in years.
Console.WriteLine($"{name}, you are {(int)(ageInYears * 365.25)} days old!"); // We compute, truncate, and display the age in days.

Problem 6

Both problems asked to develop fairly straightforward classes. The answers can be read from the following code:

// Section A
class Item {
  private decimal price; // To hold the price of the item.
  private string description; // To hold a description of the item.
  public decimal GetPrice() {
    return price;
  }
  public void SetDescription(string descriptionP) {
    description = descriptionP;
  }
  public decimal GetMultiplePrice(int quantity) {
    return quantity * price;
  }
  // The following was not asked
  public void SetPrice(decimal priceP) {
    price = priceP;
  }
}

// Section B
class Bottle {
  private string content; // To hold a description of the content.
  private int oz; // To hold the capacity in ounces.
  public int GetOz() {
    return oz;
  }
  public void SetContent(string contentP) {
    content = contentP;
  }
  public double GetPint() {
    return oz / 16;
  }
  // The following was not asked
  public void SetOz(int ozP) {
    oz = ozP;
  }
}
using System;

class Welcome {
  static void Main() {
    // Section A
    Item myItem = new Item();
    // The following was not asked
    myItem.SetPrice(19.99M);
    Console.WriteLine($ "{myItem.GetPrice():C}");
    Console.WriteLine("Please, enter a description.");
    myItem.SetDescription(Console.ReadLine());
    Console.WriteLine($ "{myItem.GetMultiplePrice(5):C}");
    // Section B
    Bottle myBottle = new Bottle();
    // The following was not asked
    myBottle.SetOz(32);
    Console.WriteLine($ "{myBottle.GetOz()}");
    Console.WriteLine("Please, enter a content description.");
    myBottle.SetContent(Console.ReadLine());
    Console.WriteLine($ "{myBottle.GetPint()}");
  }
}

As an exercise, try to set up those three pieces of codes (that is, the Item, Bottle, and Welcome classes) in a project in Visual Studio, and check that it works as expected.