Dotnet Concepts

.NET Concepts

1. Namespace

A namespace is a container that holds classes, interfaces, structs, enums, and other namespaces.

Purpose:

• Logically group related classes and types
• Avoid naming conflicts
• Improve code readability and maintainability

Common Use Cases:

• Organizing layers: Models, Services, Controllers
• Separating business logic from data access
• Grouping helper methods or extensions

Key Points:

• Use namespace keyword
• Supports nested namespaces
• Reference with using directive
• Namespace can span multiple files

Types:

• System: Built-in (e.g., System.Linq)
• User-defined: e.g., MyApp.Services

2. GC (Garbage Collector)

The Garbage Collector (GC) in .NET automatically reclaims memory used by unreferenced objects.

How It Works:

• CLR tracks object references
• When needed, GC reclaims unused memory
• Runs in background or on low memory triggers

Triggering Conditions:

• Memory usage crosses a threshold
• Explicit call: GC.Collect() (not recommended)
• App is idle or background threads free

3. CLR (Common Language Runtime)

The CLR is the runtime engine that manages the execution of .NET programs.

Responsibilities:

• Memory management via GC
• JIT Compilation and execution
• Exception handling
• Thread management & security

GC vs CLR Comparison

Feature	GC (Garbage Collector)	CLR (Common Language Runtime)
Role	Manages memory	Executes .NET applications
Scope	Part of CLR	Entire runtime environment
Manual Control	Minimal (GC.Collect())	None
Developer Involvement	None required	Write managed code

4. Variable vs Field vs Property

Concept	Scope/Location	Usage	Access Control
Variable	Inside method/block	Temporary data	Local only
Field	Inside class/struct	Stores object state	Accessible in class
Property	Inside class (with accessors)	Encapsulates field	Controlled access (get/set)

public int Age { get; set; }

5. Enum in C#

Enum defines a set of named constants backed by integers.

enum Status { Active, Inactive, Suspended }
Status userStatus = Status.Active;

Pros:

• Improves code readability and type safety
• Works well with switch-case
• Supports metadata via attributes

Cons:

• No methods or behavior
• Static and limited to constants
• Not ideal for dynamic lists

6. Reflection in C#

Reflection allows runtime access to metadata, types, methods, and more.

var type = typeof(MyClass);
var methods = type.GetMethods();
foreach (var method in methods)
{
    Console.WriteLine(method.Name);
}

Pros:

• Dynamic behavior
• Frameworks, DI containers, and tools rely on it

Cons:

• Slower performance
• Runtime errors possible
• Can expose internals

Enum vs Reflection

Feature	Enum	Reflection
Purpose	Define fixed constants	Inspect metadata dynamically
Type	Value type	API: System.Reflection
Use Case	Status codes, roles	Metadata, dynamic access

7. Task, async, await in C#

Task represents an asynchronous operation.
async marks a method as asynchronous.
await waits for the task without blocking.

public async Task<string> GetDataAsync()
{
    await Task.Delay(1000);
    return "Hello World";
}

Use Cases:

• Database calls
• HTTP requests
• File I/O
• Sending emails

8. const vs readonly

Feature	const	readonly
Set Time	Compile-time	Runtime (constructor)
Modifiable	No	Once during initialization
Scope	Always static	Can be instance-level
Type	Primitive/string	Any type