C# - Syntax

C# (pronounced C-sharp) is a statically typed, object-oriented programming language developed by Microsoft. It is widely used for developing a range of applications, from web and desktop apps to games and cloud services. Here’s an overview of C# syntax, covering basic constructs and concepts.

Basic Syntax

1. Hello World Program

csharp
using System;  // Import the System namespace

class Program
{
    static void Main()
    {
        Console.WriteLine("Hello, World!");
    }
}

using System; imports the System namespace.
class Program defines a class named Program.
static void Main() is the entry point of a C# application.

Variables and Data Types

2. Declaring Variables

csharp
int number = 10;
double price = 19.99;
char initial = 'A';
string name = "Alice";
bool isActive = true;

Primitive Types: int, double, char, bool
Non-Primitive Type: string

3. Constants

csharp
const double Pi = 3.14159;

const declares a constant value that cannot be changed.

Control Flow

4. Conditional Statements

csharp
int age = 20;

if (age >= 18)
{
    Console.WriteLine("Adult");
}
else
{
    Console.WriteLine("Minor");
}

5. Switch Statement

csharp
int day = 3;

switch (day)
{
    case 1:
        Console.WriteLine("Monday");
        break;
    case 2:
        Console.WriteLine("Tuesday");
        break;
    case 3:
        Console.WriteLine("Wednesday");
        break;
    default:
        Console.WriteLine("Weekend");
        break;
}

Loops

6. For Loop

csharp
for (int i = 0; i < 5; i++)
{
    Console.WriteLine(i);
}

7. While Loop

csharp
int count = 0;

while (count < 5)
{
    Console.WriteLine(count);
    count++;
}

8. Do-While Loop

csharp
int number = 0;

do
{
    Console.WriteLine(number);
    number++;
} while (number < 5);

Functions and Methods

9. Defining and Calling Methods

csharp
public class MathOperations
{
    public int Add(int a, int b)
    {
        return a + b;
    }
}

class Program
{
    static void Main()
    {
        MathOperations math = new MathOperations();
        int result = math.Add(5, 7);
        Console.WriteLine(result);
    }
}

public int Add(int a, int b) defines a method that returns an integer.
static void Main() is where execution starts.

Classes and Objects

10. Defining a Class

csharp
public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }

    public void Greet()
    {
        Console.WriteLine($"Hello, my name is {Name} and I am {Age} years old.");
    }
}

class Program
{
    static void Main()
    {
        Person person = new Person();
        person.Name = "John";
        person.Age = 30;
        person.Greet();
    }
}

Inheritance

11. Base and Derived Classes

csharp
public class Animal
{
    public void Eat()
    {
        Console.WriteLine("Eating...");
    }
}

public class Dog : Animal
{
    public void Bark()
    {
        Console.WriteLine("Woof!");
    }
}

class Program
{
    static void Main()
    {
        Dog dog = new Dog();
        dog.Eat();
        dog.Bark();
    }
}

Interfaces

12. Defining and Implementing Interfaces

csharp
public interface IDrivable
{
    void Drive();
}

public class Car : IDrivable
{
    public void Drive()
    {
        Console.WriteLine("Car is driving.");
    }
}

class Program
{
    static void Main()
    {
        IDrivable drivable = new Car();
        drivable.Drive();
    }
}

Collections

13. Arrays

csharp
int[] numbers = { 1, 2, 3, 4, 5 };
foreach (int number in numbers)
{
    Console.WriteLine(number);
}

14. Lists

csharp
using System.Collections.Generic;

List<string> names = new List<string> { "Alice", "Bob", "Charlie" };
names.Add("David");

foreach (string name in names)
{
    Console.WriteLine(name);
}

Exception Handling

15. Try-Catch

csharp
try
{
    int[] array = new int[5];
    array[10] = 1;  // This will throw an exception
}
catch (IndexOutOfRangeException ex)
{
    Console.WriteLine("An error occurred: " + ex.Message);
}
finally
{
    Console.WriteLine("Execution completed.");
}

LINQ (Language Integrated Query)

16. Basic LINQ Query

csharp
using System.Linq;

int[] numbers = { 1, 2, 3, 4, 5 };

var evenNumbers = from number in numbers
                   where number % 2 == 0
                   select number;

foreach (var number in evenNumbers)
{
    Console.WriteLine(number);
}

Summary

C# syntax is designed to be familiar to users of other C-based languages (like C++ and Java) while incorporating modern features. It supports object-oriented programming, strong typing, and a range of features that make it suitable for various application development needs.

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