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Phase 1: Day 1-2 Exercises

Primary Constructors​

Exercise 1: Basic Primary Constructor​

Create a Person class using primary constructors that:

  • Takes firstName, lastName, and age parameters
  • Exposes FullName as a computed property
  • Has a method Introduce() that uses the parameters

Expected behavior:

var person = new Person("John", "Doe", 30);
Console.WriteLine(person.FullName);  // "John Doe"
person.Introduce();  // "Hi, I'm John Doe, 30 years old"

Exercise 2: Primary Constructor with Additional Constructor​

Create a Product class with:

  • Primary constructor: Product(string name, decimal price, string category)
  • Additional constructor: Product(string name, decimal price) that defaults category to "General"
  • Property Name exposed publicly
  • Method Display() that shows all information

Exercise 3: Dependency Injection Pattern​

Create these classes:

  • Interface ILogger with method Log(string message)
  • Class ConsoleLogger implementing ILogger
  • Class OrderService with primary constructor taking ILogger
  • The service should log messages when processing orders

Exercise 4: Primary Constructor with Validation​

Create an Email class that:

  • Takes address as primary constructor parameter
  • Validates the email in the property initializer
  • Throws ArgumentException for invalid emails
  • Exposes Domain property (e.g., "example.com" from "user@example.com")

Collection Expressions​

Exercise 5: Basic Collection Expressions​

Create examples using collection expressions for:

  • An array of integers
  • A List of strings
  • A Span of doubles
  • An empty collection

Exercise 6: Spread Operator​

Write a method MergeArrays(int[] arr1, int[] arr2, int[] arr3) that:

  • Uses collection expressions and spread operator
  • Returns a single array containing all elements
  • Adds 0 at the beginning and 999 at the end

Example:

int[] result = MergeArrays([1, 2], [3, 4], [5, 6]);
// Result: [0, 1, 2, 3, 4, 5, 6, 999]

Exercise 7: Conditional Collection Building​

Create a method BuildConfiguration(bool includeDebug, bool includeVerbose) that:

  • Returns a List<string> with configuration flags
  • Always includes "Production"
  • Conditionally includes "Debug" and "Verbose" based on parameters
  • Uses collection expressions with spread operator

Exercise 8: Collection Types​

Create a method DemonstrateCollectionTypes() that shows the same data [1, 2, 3, 4, 5] used as:

  • int[]
  • List<int>
  • Span<int>
  • ImmutableArray<int>

Demonstrate operations on each type and explain when to use each.

Combined Exercises​

Exercise 9: Event Registration System​

Create an event registration system with:

  • Event class using primary constructor (name, date, maxCapacity)
  • Attendee class using primary constructor (name, email)
  • Collection expressions to manage attendee lists
  • Methods to add/remove attendees

Exercise 10: Data Aggregator​

Create a DataAggregator class that:

  • Has primary constructor taking ILogger
  • Has method Aggregate(List<int> cache, int[] newData, Span<int> buffer)
  • Uses collection expressions to combine all data sources
  • Logs the aggregation process
  • Returns deduplicated results

Bonus Challenges​

Challenge 1: Performance Comparison​

Write a benchmark comparing:

  • Traditional array initialization vs collection expressions
  • List initialization vs collection expressions
  • Span allocation with collection expressions vs stackalloc

Challenge 2: Real-World Scenario​

Build a simple shopping cart system using:

  • Primary constructors for Product, CartItem, ShoppingCart
  • Collection expressions for managing cart items
  • Spread operator for merging saved carts
  • Proper validation in constructors

Requirements:

  • Add/remove items
  • Calculate total
  • Apply discount codes
  • Merge multiple carts
  • Display cart summary

Testing Your Solutions​

For each exercise:

  1. Write the implementation
  2. Create test cases with various inputs
  3. Handle edge cases (null, empty, invalid data)
  4. Add XML documentation comments

Self-Assessment Questions​

After completing exercises, answer:

  1. When should you use primary constructors vs traditional constructors?
  2. Do primary constructor parameters become properties automatically?
  3. How do collection expressions improve code readability?
  4. When is the spread operator useful?
  5. What's the performance benefit of using Span with collection expressions?

Solutions Check​

Your code should demonstrate:

  • ✅ Proper use of primary constructor syntax
  • ✅ Understanding of parameter scope in primary constructors
  • ✅ Chaining additional constructors correctly
  • ✅ Using collection expressions for different collection types
  • ✅ Effective use of spread operator
  • ✅ Appropriate error handling and validation
  • ✅ Clean, readable code following C# conventions