[C#] Implement new Concept Exercise: dictionaries

[ErikSchierboom]

This issue describes how to implement the dictionaries concept exercise for the C# track.

Getting started

Please please please read the docs before starting. Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:

• The features of v3.
• Rationale for v3.
• What are concept exercise and how they are structured?

Please also watch the following video:

• The Anatomy of a Concept Exercise.

Goal

The goal of this exercise is to teach the student the basics of the Concept of Dictionaries in C#.

Learning objectives

• Know of the existence of the Dictionary<TKey, TElement> type.
• Know how to define a dictionary.
• Know how to add and updated elements in a dictionary.
• Know how to access elements in a dictionary by key.
• Know how to iterate over elements in a dictionary.
• Know some basic dictionary functions (like checking if a key exists).

Out of scope

• Generic functions.
• Generic constraints.
• Memory and performance characteristics.
• LINQ.
• Concurrency issues.
• Co-/contravariance.
• Equality.
• The Lookup<TKey, TElement> type.

Concepts

This Concepts Exercise's Concepts are:

• dictionaries: know of the existence of the Dictionary<TKey, TElement> type; know how to define a dictionary; know how to add and updated elements in a dictionary; know how to access elements in a dictionary by key; know how to iterate over elements in a dictionary; know some basic dictionary functions.

Prequisites

This Concept Exercise's prerequisites Concepts are:

• foreach-loops: know how to use a foreach-loop to iterate over a collection.
• generic-types: know how generic types work.

Any data types used in this exercise (e.g. strings) should also be added as prerequisites.

Resources to refer to

Hints

• Dictionaries documentation: reference documentation for Dictionary<TKey, TElement>.
• Dictionaries tutorial: basic tutorial on how to work with dictionaries.

After

• Dictionaries documentation: reference documentation for Dictionary<TKey, TElement>.
• Dictionaries tutorial: basic tutorial on how to work with dictionaries.

Representer

This exercise does not require any specific representation logic to be added to the representer.

Analyzer

This exercise does not require any specific analyzer logic to be added to the analyzer.

Implementing

To implement this exercise, please follow these instructions.

Help

If you have any questions while implementing the exercise, please post the questions as comments in this issue.

[archrisV]

Sorry, I've accidentally assigned myself to the wrong exercise yesterday.

[ErikSchierboom]

No worries.

[mikedamay]

I will create this exercise

[ErikSchierboom]

Great!

[ErikSchierboom]

@mikedamay We've also been updating the documentation lots. E.g. the C# implementing docs and the general implementing docs have both been updated and now both refer to file description in the concept exercises document. Finally, we've also added (and linked to) a style guide. It would be interesting to see if these changes resolve the issues you've found creating the properties exercise.