/C-Sharp-Basic-Collection

Introduction to C#

Primary LanguageC#

C# Basic Collection

Introduction to C# and basic data types

Practice: Planet and Spaceships

Instructions

In the Main method, place the following code

List<string> planetList = new List<string>(){"Mercury", "Mars"};
  1. Add() Jupiter and Saturn at the end of the list.
  2. Create another List that contains that last two planet of our solar system.
  3. Combine the two lists by using AddRange().
  4. Use Insert() to add Earth, and Venus in the correct order.
  5. Use Add() again to add Pluto to the end of the list.
  6. Now that all the planets are in the list, slice the list using GetRange() in order to extract the rocky planets into a new list called rockyPlanets. The rocky planets will remain in the original planets list.
  7. Being good amateur astronomers, we know that Pluto is now a dwarf planet, so use the Remove() method to eliminate it from the end of planetList.

Practice: Random Numbers

Instructions

  1. Use the following code to create a list of random numbers. Each number will be between 0 and 9. 
    Random random = new Random();
List<int> numbers = new List<int> {
    random.Next(10),
    random.Next(10),
    random.Next(10),
    random.Next(10),
    random.Next(10),
};
  2. Use a for loop to iterate over all numbers between 0 and numbers.Count - 1.
  3. Inside the body of the for loop determine if the current loop index is contained inside of the numbers list. Print a message to the console indicating whether the index is in the list.

Example Output in the Terminal

numbers list contains 0
numbers list does not contain 1
numbers list does not contain 2
numbers list contains 3
numbers list contains 4

NOTE: Each run will produce different output.

Practice: Stock Purchase Dictionaries

References

Instructions

A block of publicly traded stock has a variety of attributes, we'll look at a few of them. A stock has a ticker symbol and a company name. Create a simple dictionary with ticker symbols and company names in the Main method.

Example
Dictionary<string, string> stocks = new Dictionary<string, string>();
stocks.Add("GM", "General Motors");
stocks.Add("CAT", "Caterpillar");
// Add a few more of your favorite stocks

To find a value in a Dictionary, you can use square bracket notation much like JavaScript object key lookups.

string GM = stocks["GM"];   <--- "General Motors"

Next, create a list to hold stock purchases by an investor. The list will contain dictionaries.

List<Dictionary<string, double>> purchases = new List<Dictionary<string, double>>();

Then add some purchases.

Example
purchases.Add (new Dictionary<string, double>(){ {"GE", 230.21} });
purchases.Add (new Dictionary<string, double>(){ {"GE", 580.98} });
purchases.Add (new Dictionary<string, double>(){ {"GE", 406.34} });

// Add more purchases for each stock

Create a total ownership report that computes the total value of each stock that you have purchased. This is the basic relational database join algorithm between two tables.

Helpful Links: ContainsKey, Add

/*
    Define a new Dictionary to hold the aggregated purchase information.
    - The key should be a string that is the full company name.
    - The value will be the total valuation of each stock


    From the three purchases above, one of the entries
    in this new dictionary will be...
        {"General Electric", 1217.53}

    Replace the questions marks below with the correct types.
*/
Dictionary<?, ?> stockReport = new Dictionary<?, ?>();

/*
   Iterate over the purchases and record the valuation
   for each stock.
*/
foreach (Dictionary<string, double> purchase in purchases) {
{
    foreach (KeyValuePair<string, double> stock in purchase)
    {
        // Does the full company name key already exist in the `stockReport`?

        // If it does, update the total valuation

        /*
            If not, add the new key and set its value.
            You have the value of "GE", so how can you look
            the value of "GE" in the `stocks` dictionary
            to get the value of "General Electric"?
        */
    }
}

Now that the report dictionary is populated, display the final results.

foreach(KeyValuePair<?, ?> item in stockReport)
{
    Console.WriteLine($"The position in {display the key} is worth {display the value}");
}

Instructions

Ref: List of Solar System probes

  1. Use the list of planets you created in the previous chapter or create a new one with all eight planets.

    List<string> planetList = new List<string>(){"Mercury", "Venus", "Earth", ...};

  2. Create another list containing dictionaries. Each dictionary will hold the name of a spacecraft that we have launched, and the name of the planet that it has visited. If it visited more than one planet, just pick one.

    List<Dictionary<string, string>> probes = new List<Dictionary<string, string>>();

  3. Iterate over planetList, and inside that loop, iterate over the list of dictionaries. Write to the console, for each planet, which satellites have visited which planet.

    foreach () // iterate planets
{
    List<string> matchingProbes = new List<string>();

    foreach() // iterate probes
    {
        /*
            Does the current Dictionary contain the key of
            the current planet? Investigate the ContainsKey()
            method on a Dictionary.

            If so, add the current spacecraft to `matchingProbes`.
        */
    }

    /*
        Use String.Join(",", matchingProbes) as part of the
        solution to get the output below. It's the C# way of
        writing `array.join(",")` in JavaScript.
    */
    Console.WriteLine($"{}: {}");
}

Example Output in the Terminal

Mars: Viking, Opportunity, Curiosity
Venus: Mariner, Venera