C# Introduction

Key C# Features

class Car
{
    public string Brand;
}

int age = 25;
string name = "John";

for(int i = 0; i < 1000; i++)
{
    // Fast loop
}

using System;
using System.Linq;
using System.IO;

🔹 C# Program Structure

Every C# program is organized within namespaces, classes, and methods, starting execution at the Main method. A typical structure includes: using System;, namespace MyApp { class Program { static void Main() { Console.WriteLine("Hello"); } } }. The Main method is the entry point. This structured approach ensures code modularity, reusability, and clear separation of concerns, which is essential for building scalable applications.

using System;  // Import namespace

namespace MyApp  // Define namespace
{
    class Program  // Define class
    {
        static void Main(string[] args)  // Main method
        {
            Console.WriteLine("Hello World!");
        }
    }
}

🔹 Variables and Data Types

C# is statically typed, meaning every variable must declare its data type before use. Common types include int for integers, string for text, double for decimals, and bool for true/false values. For example: int age = 25; string name = "Alice";. Type safety prevents errors by catching mismatches at compile time. Understanding data types is fundamental for efficient memory usage and robust application development in C#.

using System;

class DataTypes
{
    static void Main()
    {
        // Integer
        int age = 25;
        
        // Decimal
        double price = 19.99;
        
        // Text
        string name = "Alice";
        
        // True/False
        bool isStudent = true;
        
        Console.WriteLine("Name: " + name);
        Console.WriteLine("Age: " + age);
        Console.WriteLine("Price: $" + price);
        Console.WriteLine("Student: " + isStudent);
    }
}

🔹 Basic Operations

C# supports arithmetic, concatenation, and comparison operators to perform calculations and evaluations. Arithmetic includes +, -, *, /. String concatenation uses +, like "Hello" + "World". Comparisons (>, ==, <=) return Boolean results. For example: int sum = 10 + 5; or bool isGreater = 10 > 5;. These operations form the core logic for data manipulation and decision-making in programs.

using System;

class Operations
{
    static void Main()
    {
        // Math operations
        int sum = 10 + 5;
        int product = 10 * 5;
        
        // String concatenation
        string greeting = "Hello" + " " + "World";
        
        // Comparison
        bool isGreater = 10 > 5;
        
        Console.WriteLine("Sum: " + sum);
        Console.WriteLine("Product: " + product);
        Console.WriteLine(greeting);
        Console.WriteLine("10 > 5: " + isGreater);
    }
}

🔹 Why Choose C#?

C# is a versatile, modern language ideal for desktop, web, mobile, and game development, particularly within the .NET ecosystem. Its strong typing reduces runtime errors, while features like LINQ, async/await, and garbage collection boost productivity. Backed by Microsoft with extensive documentation and community support, C# offers excellent performance, scalability, and cross-platform capabilities via .NET Core. It's a top choice for building enterprise applications, Unity games, and cloud services.

🔹 C# vs Other Languages

Understanding how C# compares to languages like Java, Python, and JavaScript helps in selecting the right tool for a project. C# and Java share similar syntax, but C# offers more modern features like properties and events. Compared to Python, C# is faster and type-safe but requires more verbose code. Against JavaScript, C# is compiled and server-side, while JS is interpreted and client-side. Each language excels in different domains—C# in robust, scalable systems.