C# is a powerful, versatile programming language widely used in the United States and beyond. Whether you're a beginner or an experienced developer, understanding core C# concepts is essential for creating efficient and maintainable software. In this blog, we'll explore various topics such as collections in C#, Fluent Validation in .NET Core, and design patterns with practical examples. We'll also touch upon key principles and techniques like the Open/Closed Principle, lambda expressions, and more.

Collections in C#

Collections in C# are vital for managing groups of objects. For instance, the HashMap and Dictionary in C# are fundamental data structures. Both are used to store key-value pairs, but they differ in implementation and performance characteristics. The Dictionary is a commonly used collection due to its efficient lookups and insertions.

Here's a quick example of using a Dictionary in C#:

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var dictionary = new Dictionary<string, int>

{

    {"Alice", 30},

    {"Bob", 25}

};

Console.WriteLine(dictionary["Alice"]); // Output: 30

If you're interested in more details about collections, visit C# Collections.

Global Exception Handler in .NET Core

In .NET Core, managing exceptions globally is crucial for maintaining application stability. A Global Exception Handler can be implemented using middleware in your ASP.NET Core application. This approach ensures that any unhandled exceptions are captured and managed in a consistent manner.

Here’s an example of a simple Global Exception Handler:

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public void Configure(IApplicationBuilder app, IHostingEnvironment env)

{

    app.UseExceptionHandler("/Home/Error");

    app.UseHsts();

    // other configurations

}

For more on handling exceptions, check out our article on Global Exception Handling in .NET Core.

Fluent Validation in .NET Core

Fluent Validation is a library that simplifies the validation of objects in .NET Core applications. It provides a fluent interface for defining validation rules, making the code more readable and maintainable.

Here's an example of using Fluent Validation:

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public class UserValidator : AbstractValidator<User>

{

    public UserValidator()

    {

        RuleFor(x => x.Name).NotEmpty();

        RuleFor(x => x.Age).GreaterThan(0);

    }

}

Explore more about Fluent Validation on our Fluent Validation in .NET Core page.

Understanding Design Patterns in C#

Design patterns are essential for creating scalable and maintainable code. In C#, some of the most commonly used design patterns include Singleton, Factory, and Observer patterns.

Here’s an example of the Singleton pattern:

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public class Singleton

{

    private static Singleton _instance;

    private Singleton() {}

    public static Singleton Instance

    {

        get

        {

            if (_instance == null)

            {

                _instance = new Singleton();

            }

            return _instance;

        }

    }

}

For a deeper dive into design patterns, check out our article on Design Patterns in C# with Examples.

Key Principles and Techniques

Understanding principles like the Open/Closed Principle and Liskov Substitution Principle is crucial for writing robust code. For example, the Open/Closed Principle states that software entities should be open for extension but closed for modification.

Difference Between Async and Await in C#

Async and Await keywords are used to handle asynchronous programming in C#. Async marks a method as asynchronous, while Await is used to pause the execution until the awaited task is complete. This approach enhances performance and responsiveness in applications.

Boxing and Unboxing in C#

Boxing is the process of converting a value type to an object type, while unboxing converts an object type back to a value type. This is useful when working with generic collections or APIs that use object.

What is Delegate in C# with Example

Delegates in C# are type-safe function pointers. They are used to pass methods as parameters. Here’s a basic example:

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public delegate void PrintDelegate(string message);

public class Program

{

    public static void PrintMessage(string message)

    {

        Console.WriteLine(message);

    }

    static void Main()

    {

        PrintDelegate print = PrintMessage;

        print("Hello, World!");

    }

}

Conclusion

Mastering these C# concepts will greatly enhance your development skills. From collections and validation to design patterns and principles, each topic plays a crucial role in building robust applications. For more resources and detailed examples, visit C# Master.