C# The programming language Intermediate

This course builds on the foundations of C# programming, introducing advanced object-oriented programming techniques and key features of the .NET Framework and .NET Core. Designed for learners who have completed the C# Fundamentals course or have equivalent experience, it takes participants deeper into inheritance, abstract classes, interfaces, delegates, lambda expressions, LINQ, and database connectivity with Entity Framework. Learners will also gain the skills to implement robust error handling and work effectively with data and files. By focusing on console applications, class libraries, unit test projects, and database-first Entity Framework techniques, the course equips developers with practical, transferable skills to create maintainable, scalable solutions. Sessions combine lectures, demonstrations, and hands-on exercises, ensuring learners can apply new concepts immediately.

Prerequisites

Learners should have:

• Knowledge of C# equivalent to QA’s C# Fundamentals course, including methods, properties, and constructors
• Basic understanding of object-oriented principles such as abstraction and encapsulation
• Familiarity with Visual Studio or similar development environments

Target audience

This course is designed for:

• Developers with existing C# experience seeking to advance their skills
• Professionals building .NET Framework or .NET Core applications who need to apply advanced language features
• Programmers aiming to enhance application maintainability and scalability through advanced C# techniques

By the end of this course, learners will be able to:

• Create derived classes that inherit from custom or .NET base classes
• Apply polymorphism effectively through abstract classes and interfaces
• Implement and consume delegates, including built-in delegate types
• Use lambda expressions to streamline code and improve readability
• Connect to databases using Entity Framework in a database-first approach
• Query and manipulate data using LINQ with best practice techniques
• Handle exceptions effectively to build robust applications
• Work with data collections and files within .NET applications

Review of object-oriented programming principles

• Why object orientation matters
• Recap of core concepts: abstraction, encapsulation, inheritance, and polymorphism
• Classes, instances, and the ‘this’ keyword
• Handling null references

Inheritance and abstract classes

• Creating and working with derived classes
• Polymorphism and virtual members
• Overriding methods and invoking base class functionality
• Abstract classes and their use cases
• Casting techniques: up-casting, down-casting, and the is/as operators

Working with interfaces

• Defining and implementing interfaces
• Achieving polymorphism with interfaces
• Implementing multiple interfaces

Delegates and lambda expressions

• Understanding delegates and their purpose
• Built-in delegate types: Func, Action, and Predicate
• Creating and using lambda expressions
• Practical examples combining delegates and lambdas

Database access with Entity Framework

• Overview of ORM principles
• Database-first vs code-first approaches
• Configuring models, connection strings, and contexts
• Querying and updating data
• Introduction to LINQ in Entity Framework
• Using appsettings.json for configuration
• IEnumerable vs IQueryable considerations

Language Integrated Query (LINQ)

• Syntax fundamentals and query patterns
• Projections and transformations
• Deferred vs immediate execution
• Joins, aggregations, and group joins
• Using the let clause and OfType method
• LINQ best practices

Exception handling

• try, catch, finally, and throw keywords
• Understanding execution flow during exceptions
• Throwing and rethrowing exceptions
• Creating and using custom exception types

Exams and assessments

There are no formal exams for this course. Learners will complete practical coding tasks, targeted challenges, and interactive exercises to validate their understanding of key concepts.

Hands-on learning

This course includes:

• Guided coding exercises for advanced object-oriented techniques
• Practical examples of delegates, lambdas, and LINQ queries
• Configuring and querying databases using Entity Framework
• Real-world error handling scenarios to improve application resilience