Lecture Notes on C# Basics

Introduction

• Lecturer: Mike
• Course: Introduction to C#
• Overview: Learn the basics of C# including installation, programming concepts, data structures, and advanced topics such as object-oriented programming.
• Applications: Extensive use in various software applications worldwide.

Getting Started

Installation and Setup

• Tools Required: Visual Studio Community
• Steps:
  1. Download Visual Studio Community from visualstudio.com
  2. Install dotnet desktop development with size around 3GB
  3. Launch Visual Studio
  4. Choose settings and start a new console application project in C#
• First Program: Basic template provided by Visual Studio (program.cs)

Basics of C# Programming

Printing to Console

• Example Code: Console.WriteLine("Hello World"); Console.ReadLine(); // To keep the console window open

Drawing Shapes

• Print shapes using multiple WriteLine statements to draw e.g., a triangle.

Variables and Data Types

• String: Represent text values
• Character: Single character
• Integer (int): Whole numbers
• Double: Decimal numbers
• Boolean (bool): True or false values

Working with Strings

• Concatenation: Using + to combine strings
• **Useful Methods: **
  • .Length: Get length of a string
  • .ToUpper(): Convert to uppercase
  • .Contains(): Check if substring is present
  • .Substring(startIndex, length): Extract part of a string

Numbers and Math Operations

• Basic operations: +, -, *, /, %
• Useful Methods from Math Library: .Abs(), .Pow(), .Sqrt(), .Max(), .Min(), .Round()*

User Input

• Usage: Console.ReadLine()
• Convert input to appropriate type using Convert.To<type>()
• Creating simple programs to add/subtract/multiply/divide numbers based on user input.

Control Structures

If-Statements

• Basic usage to check conditions if (condition) { // Execute this if condition is true } else { // Execute this if condition is false }
• Comparisons using logical operators: >, <, >=, <=, ==, !=, &&, ||
• Complex if-else structures to handle multiple conditions

Switch Statements

• Used to simplify complex if-else statements for checking multiple conditions switch(variable) { case value1: // Code block break; case value2: // Code block break; default: // Code block break; }

Loops

While Loops

• Repeat a block of code while a condition is true while (condition) { // Code block }

Do-While Loops

• Similar to while, but guarantees the block executes at least once do { // Code block } while (condition)

For Loops

• Initialize, condition, and increment in a single line for (int i = 0; i < limit; i++) { // Code block }

Exception Handling

• Try-Catch Blocks: Handle errors to prevent program crashes try { // Code block } catch (Exception e) { Console.WriteLine(e.Message); } finally { // Code block }
• Multiple catches for specific exceptions (e.g., DivideByZeroException, FormatException)

Object-Oriented Programming

Classes and Objects

• Class Definition: Blueprint for data types public class ClassName { public string attributeName; public ClassName(string parameterName) { this.attributeName = parameterName; } }
• Object Creation: Instantiate and use objects ClassName obj = new ClassName("value"); Console.WriteLine(obj.attributeName);

Constructors

• Special methods invoked during object creation for initializing attributes

Object Methods

• Define methods within classes to perform operations public class ClassName { public bool MethodName() { // Code block } }

Getters and Setters

• Control access to attributes using properties private string varName; public string VarName { get { return varName; } set { varName = value; } }

Static Attributes and Methods

• Static Attributes: Shared across all instances of a class public static int count = 0;
• Static Methods: Called on the class itself rather than instances public static void StaticMethod() { // Code block }

Inheritance

• Derive a class from another class, inheriting attributes and methods public class SubClass : SuperClass { // Additional or overridden functionality }
• Method Overriding: Override a superclass method in a subclass using virtual and override keywords public virtual void SomeMethod() { // Code block } public override void SomeMethod() { // New code block }

Conclusion

• Extensive potential applications in software development
• Encourage further exploration and practice of C# concepts