
Delve into .NET development with C#, covering programming fundamentals, object-oriented principles, exception handling, and multithreading. Gain hands-on experience to build cross-platform applications effectively.

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.NET is Microsoft’s free and open source framework for developing native software applications on Linux, macOS, and Windows. The power of cross-platform development allows developers to design, code, and run programs on a wide array of platforms.

This course is an introduction to developing .NET applications using C#. You’ll start start with a comprehensive review of C# and computer programming fundamentals: data types, conditionals, loops, methods, and more. You’ll then review the basics of object-oriented programming before diving into methods, exception handling, delegation, and events. With this foundation, you’ll continue building interfaces, collections, database operations, and multithreading. You’ll wrap up with process improvements using dynamic binding, garbage collection, and unmanaged resources.

By the end of this course, you’ll have hands-on experience with C# and .NET, and be ready to build applications using object-oriented programming principles on almost any platform.

Mastering C# and .NET

## Introduction

There are subtleties regarding the timing of LINQ query execution. There are essentially two ways of executing a LINQ query:

 - **Deferred execution**: The LINQ query only executes when we try to address an item from a resulting collection.

 - **Immediate execution**: The LINQ query executes immediately after construction.

Let’s explore these in detail.

## Deferred execution

There are three steps to creating and running a LINQ query:
 1. Creating or attaining a data source
 2. Creating a query
 3. Executing the query

Deferred execution means that our query isn’t executed the moment it’s created:

```C#
// Step 1. Creating or attaining a data source
var countryList = new List<string>()
{
    "Germany", "Thailand", "France", "Spain",
    "Italy", "United States", "Romania", "Russia",
    "Greece", "Argentina", "Canada", "Mexico",
    "Ireland", "Albania", "Slovenia", "Kazakhstan"
};

// Step 2. Creating a query
var countriesThatStartWithC = from country in countryList
                                where country.StartsWith("C")
                                select country;

// But the query hasn't run yet!
```

Rather, the query runs when we want to access an element inside the resulting collection:

```C#
// The query is run here and the result is stored in the variable
Console.WriteLine(countriesThatStartWithC[0]); // Canada
```

To prove that the query doesn't run until we access an element in the resulting collection, we can try to alter the data source after we construct the query:

# Introduction

There are subtleties regarding the timing of LINQ query execution. There are essentially two ways of executing a LINQ query:

 - **Deferred execution**: The LINQ query only executes when we try to address an item from a resulting collection.

 - **Immediate execution**: The LINQ query executes immediately after construction.

Let’s explore these in detail.

# Deferred execution

There are three steps to creating and running a LINQ query:
 1. Creating or attaining a data source
 2. Creating a query
 3. Executing the query

Deferred execution means that our query isn’t executed the moment it’s created:

```C#
// Step 1. Creating or attaining a data source
var countryList = new List<string>()
{
    "Germany", "Thailand", "France", "Spain",
    "Italy", "United States", "Romania", "Russia",
    "Greece", "Argentina", "Canada", "Mexico",
    "Ireland", "Albania", "Slovenia", "Kazakhstan"
};

// Step 2. Creating a query
var countriesThatStartWithC = from country in countryList
                                where country.StartsWith("C")
                                select country;

// But the query hasn't run yet!
```

Rather, the query runs when we want to access an element inside the resulting collection:

```C#
// The query is run here and the result is stored in the variable
Console.WriteLine(countriesThatStartWithC[0]); // Canada
```

To prove that the query doesn't run until we access an element in the resulting collection, we can try to alter the data source after we construct the query:

Learn about when LINQ queries are executed.

Getting Started

C# Programming Basics

Classes and OOP

Classes and OOP II

Exception Handling

First Assessment

Delegates and Events

Interfaces

Additional Features

Collections

LINQ

Working with Strings

Working with Dates and Time

Multithreading and Asynchronous Programming

Reflection

Dynamic Binding

Garbage Collection and Unmanaged Resources

Final Assessment

Next Steps

Appendix

Deferred Execution

Introduction

Deferred execution