.Net Programming

1. Framework Overview

• .NET Framework: Traditional Windows-based applications.
• .NET Core: Cross-platform development (now merged into .NET 5+).
• ASP.NET: Framework for building web applications.
• Entity Framework: ORM for database interactions.

2. Common Project Types

• Console Application: Simple command-line programs.
• Web Application: Dynamic web pages (ASP.NET MVC/Razor Pages).
• Web API: RESTful services for client-server communication.
• Class Library: Reusable code modules.

3. Basic Syntax

• • Variables:
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    int number = 5;
    string name = "Hello";
    bool isActive = true;
    
    

  • Control Structures:
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    if (condition) { /* code */ }
    for (int i = 0; i < 10; i++) { /* code */ }
    foreach (var item in collection) { /* code */ }
    switch (value) { case x: /* code */ break; }
    
    

•      Methods:
  
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  public int Add(int a, int b) {
      return a + b;
  }
  
  

4. Object-Oriented Programming

• Classes and Objects:
  
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  public class Person {
      public string Name { get; set; }
      public int Age { get; set; }
  }
  
  Person person = new Person { Name = "John", Age = 30 };
  
  

• Inheritance:
  
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  public class Employee : Person {
      public string Position { get; set; }
  }
  
  

• Interfaces:
  
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  public interface IAnimal {
      void Speak();
  }
  
  public class Dog : IAnimal {
      public void Speak() {
          Console.WriteLine("Woof!");
      }
  }
  
  

5. Common Libraries

• LINQ: Query collections.
  
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  var results = collection.Where(x => x.Property == value);
  

• Async/Await: Asynchronous programming.
  
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  public async Task<string> FetchDataAsync() {
      var result = await httpClient.GetStringAsync("url");
      return result;
  }
  
  

• Dependency Injection: Used in ASP.NET Core.
  
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  services.AddScoped<IMyService, MyService>();
  

6. Error Handling

• Try-Catch:
  
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  try {
      // code that may throw
  } catch (Exception ex) {
      Console.WriteLine(ex.Message);
  }
  
  

7. Database Interaction with Entity Framework

• DbContext:
  
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  public class MyDbContext : DbContext {
      public DbSet<Person> People { get; set; }
  }
  
  

• CRUD Operations:
  
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  using (var context = new MyDbContext()) {
      // Create
      context.People.Add(new Person { Name = "Jane" });
      context.SaveChanges();
  
      // Read
      var people = context.People.ToList();
  
      // Update
      var person = context.People.First();
      person.Name = "Updated Name";
      context.SaveChanges();
  
      // Delete
      context.People.Remove(person);
      context.SaveChanges();
  }
  
  

8. ASP.NET Core Routing

• Basic Route:
  
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  app.MapGet("/api/people", () => {
      return peopleList;
  });
  
  

• Route Parameters:
  
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  app.MapGet("/api/people/{id}", (int id) => {
      return peopleList.FirstOrDefault(p => p.Id == id);
  });
  
  

9. Unit Testing

• XUnit Example:
  
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  public class MyTests {
      [Fact]
      public void Test_Add() {
          var result = Add(2, 3);
          Assert.Equal(5, result);
      }
  }
  
  

10. Common Commands

• Create a New Project:
  
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  dotnet new console -n ProjectName
  

• Build the Project:
  
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  dotnet build
  

• Run the Project:
  
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  dotnet run
  

11. Useful Resources

• Microsoft Docs: Official documentation.
• Stack Overflow: Community Q&A.
• GitHub: Open-source projects for reference.