C# Fundamentals

This section covers the fundamental building blocks of the C# programming language, essential for developing robust and efficient applications on the .NET platform.

Variables and Data Types

C# is a statically typed language, meaning that all variables must have a declared type. This helps catch errors at compile time and improves performance. Common data types include:

• int: For whole numbers.
• double: For floating-point numbers with double precision.
• bool: For boolean values (true or false).
• string: For sequences of characters.
• char: For single characters.

Example declaration:

int age = 30;
string name = "Alice";
bool isStudent = true;
double price = 19.99;
            

Operators

C# supports a wide range of operators for performing operations on variables and values:

• Arithmetic Operators: +, -, *, /, % (modulo)
• Comparison Operators: ==, !=, <, >, <=, >=
• Logical Operators: && (AND), || (OR), ! (NOT)
• Assignment Operators: =, +=, -=, *=, /=

Control Flow Statements

Control flow statements allow you to dictate the order in which code is executed. This is crucial for creating dynamic and responsive applications.

Conditional Statements

Use if, else if, and else to execute code blocks based on certain conditions.

int score = 75;
if (score >= 90) {
    Console.WriteLine("Excellent!");
} else if (score >= 70) {
    Console.WriteLine("Good job!");
} else {
    Console.WriteLine("Keep practicing.");
}
            

The switch statement provides an alternative for multi-way branching.

Loops

Loops are used to repeat a block of code multiple times.

• for loop: For iterating a specific number of times.
• while loop: For iterating as long as a condition is true.
• do-while loop: Similar to while, but the code block executes at least once.
• foreach loop: For iterating over elements in a collection.

// For loop example
for (int i = 0; i < 5; i++) {
    Console.WriteLine($"Iteration: {i}");
}

// Foreach loop example
string[] fruits = {"apple", "banana", "cherry"};
foreach (string fruit in fruits) {
    Console.WriteLine(fruit);
}
            

Methods (Functions)

Methods are blocks of reusable code that perform a specific task. They help in organizing code and promoting modularity.

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

// Calling the method
Calculator calc = new Calculator();
int sum = calc.Add(5, 3); // sum will be 8
            

Methods can have parameters and return values. The access modifiers (public, private, etc.) determine their visibility.

Classes and Objects

C# is an object-oriented programming (OOP) language. The core concepts are classes and objects.

• Class: A blueprint or template for creating objects. It defines properties (data members) and methods (behavior).
• Object: An instance of a class.

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.");
    }
}

// Creating an object
Person person1 = new Person();
person1.Name = "Bob";
person1.Age = 25;
person1.Greet(); // Output: Hello, my name is Bob and I am 25 years old.
            

Namespaces

Namespaces are used to organize code and prevent naming conflicts. The using directive allows you to use types from other namespaces without fully qualifying them.

using System; // Makes Console class available
using System.Collections.Generic; // Makes List class available

public class Example {
    public static void Main(string[] args) {
        Console.WriteLine("Working with namespaces.");
        List names = new List();
        names.Add("Charlie");
    }
}
            

This section provides a foundational understanding of C#. For more advanced topics, explore the subsequent documentation modules.

Continue to Object-Oriented Programming in C#.