C# Intermediate Concepts: Collections, Exception Handling, and Beyond 🚀

Welcome back, fellow coder! 🎉 You’ve mastered the basics of C#, and now it’s time to level up. In this article, we’ll explore intermediate concepts like collections, exception handling, and other essential tools that make your C# programs more powerful and flexible. Let’s dive in! 🏊‍♂️

Collections: Managing Groups of Data Like a Pro 📚

Think of collections as super-powered containers that help you manage and manipulate groups of items, like numbers, names, or even complex objects.

Lists: The Versatile Workhorse 🐴

A List<T> is a dynamic array that grows as needed. It’s perfect for managing a group of items.

Example: Managing a To-Do List 📝

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<string> toDoList = new List<string>();

        // Add items
        toDoList.Add("Learn C#");
        toDoList.Add("Write a blog post");
        toDoList.Add("Conquer the world 🌍");

        // Remove an item
        toDoList.Remove("Conquer the world 🌍");

        // Iterate through the list
        Console.WriteLine("To-Do List:");
        foreach (string item in toDoList)
        {
            Console.WriteLine($"- {item}");
        }
    }
}

Dictionaries: Key-Value Pair Magic 🔑

A Dictionary<TKey, TValue> lets you map keys to values, like a real-world dictionary.

Example: Tracking High Scores in a Game 🎮

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        Dictionary<string, int> highScores = new Dictionary<string, int>
        {
            { "Alice", 1500 },
            { "Bob", 1200 },
            { "Charlie", 2000 }
        };

        // Access a value by key
        Console.WriteLine($"Alice's score: {highScores["Alice"]}");

        // Add or update a key
        highScores["Diana"] = 1800;

        // Display all high scores
        Console.WriteLine("High Scores:");
        foreach (var kvp in highScores)
        {
            Console.WriteLine($"{kvp.Key}: {kvp.Value}");
        }
    }
}

Other Handy Collections

• Queue<T>: First-In-First-Out (FIFO) structure, like a line at a coffee shop. ☕
• Stack<T>: Last-In-First-Out (LIFO), like a stack of plates. 🍽️
• HashSet<T>: Stores unique items only, great for eliminating duplicates.

Exception Handling: Your Safety Net 🛡️

Errors are inevitable, but you don’t want your program to crash. Exception handling ensures your app can recover gracefully.

Try-Catch: Handling Errors Like a Pro

using System;

class Program
{
    static void Main()
    {
        try
        {
            Console.Write("Enter a number: ");
            int number = int.Parse(Console.ReadLine()); // May throw FormatException
            Console.WriteLine($"You entered: {number}");
        }
        catch (FormatException)
        {
            Console.WriteLine("Oops! That’s not a valid number. 😅");
        }
        catch (Exception ex) // Catch any other exceptions
        {
            Console.WriteLine($"Something went wrong: {ex.Message}");
        }
        finally
        {
            Console.WriteLine("Thanks for using our app!");
        }
    }
}

Common Exceptions You’ll Encounter

• FormatException: When parsing invalid input.
• NullReferenceException: When trying to access an object that’s null.
• IndexOutOfRangeException: Accessing an invalid index in an array or list.

LINQ: Data Filtering and Querying Made Easy 🧐

LINQ (Language Integrated Query) is a powerful way to work with collections, databases, and more using expressive syntax.

Example: Filtering and Sorting a List

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 5, 3, 9, 1, 7, 4 };

        // Use LINQ to filter and sort
        var evenNumbers = numbers
            .Where(n => n % 2 == 0) // Filter even numbers
            .OrderBy(n => n);       // Sort ascending

        Console.WriteLine("Even numbers (sorted):");
        foreach (var num in evenNumbers)
        {
            Console.WriteLine(num);
        }
    }
}

Asynchronous Programming: Do More, Wait Less ⏱️

C#’s async and await keywords let you perform time-consuming tasks (like downloading data) without freezing your app.

Example: Simulating a Long Task

using System;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        Console.WriteLine("Starting task...");
        await PerformLongTask(); // Non-blocking
        Console.WriteLine("Task completed!");
    }

    static async Task PerformLongTask()
    {
        await Task.Delay(3000); // Simulate 3-second delay
        Console.WriteLine("Long task finished! ⏳");
    }
}

File Handling: Read and Write Data 📂

Files are everywhere, and C# makes it easy to read from or write to them.

Example: Writing and Reading a Text File

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string filePath = "example.txt";

        // Write to a file
        File.WriteAllText(filePath, "Hello, C# World!");

        // Read from the file
        string content = File.ReadAllText(filePath);
        Console.WriteLine($"File Content: {content}");
    }
}

Practice Makes Perfect: Mini Challenges 🏋️‍♂️

Test your skills with these:

1. Shopping Cart: Create a List to store items, add/remove them, and display the total count.
2. Error-Free Calculator: Build a calculator that handles invalid inputs gracefully.
3. LINQ Explorer: Use LINQ to filter a list of products by price or category.

What’s Next?

Congratulations! 🎉 You’ve unlocked the power of collections, error handling, and more. You’re now ready to tackle advanced topics like:

• Delegates and events
• Generics
• Working with APIs

Stay tuned for our next article, where we’ll dive into advanced features and create some truly exciting projects. 🚀