The .NET language compiler for C# and Visual Basic, also known as Roslyn, along with a separate compiler for F#, is distributed as part of the .NET SDK. To use a specific version of C#, you must have at least that version of the .NET SDK installed, as shown in Table 2.2:

Let’s start by looking at the basics of the grammar and vocabulary of C#. Throughout this chapter, you will create multiple console apps, with each one showing related features of the C# language.

Understanding C# grammar

The grammar of C# includes statements and blocks. To document your code, you can use comments.

Statements

In English, we indicate the end of a sentence with a period. A sentence can be composed of multiple words and phrases, with the order of words being part of the grammar. For example, in English, we say “the black cat.”

The adjective, black, comes before the noun, cat. However, French grammar has a different order; the adjective comes after the noun...

All applications process data. Data comes in, data is processed, and then data goes out.

Data usually comes into our program from files, databases, or user input, and it can be put temporarily into variables, which will be stored in the memory of the running program. When the program ends, the data in memory is lost. Data is usually output to files and databases, or to the screen or a printer. When using variables, you should think about, firstly, how much space the variable takes up in the memory, and, secondly, how fast it can be processed.

We control this by picking an appropriate type. You can think of simple common types such as int and double as being different-sized storage boxes, where a smaller box would take less memory but may not be as fast at being processed; for example, adding 16-bit numbers might not be processed as quickly as adding 64-bit numbers on a 64-bit operating system. Some of these boxes may be stacked close by, and some may...

We have already created and used basic console apps, but we’re now at a stage where we should delve into them more deeply.

Console apps are text-based and are run at the command prompt. They typically perform simple tasks that need to be scripted, such as compiling a file or encrypting a section of a configuration file.

Equally, they can also have arguments passed to them to control their behavior.

An example of this would be to create a new console app using the F# language with a specified name instead of using the name of the current folder, as shown in the following command:

dotnet new console -lang "F#" --name "ExploringConsole"

Displaying output to the user

The two most common tasks that a console app performs are writing and reading data. We have already used the WriteLine method to output, but if we didn’t want a carriage return at the end of a line, for example, if we later wanted...

Test your knowledge and understanding by answering some questions, getting some hands-on practice, and exploring the topics covered in this chapter with deeper research.

Exercise 2.1 – Online material

Online materials can be extra content written by me for this book, or it can be references to content created by Microsoft or third parties.

Understanding async and await

C# 5 introduced two C# keywords when working with the Task type that enable easy multithreading. You can read about them and see a code example at the following link:

https://github.com/markjprice/cs13net9/blob/main/docs/ch02-async-await.md

Explore Spectre

No, not the villainous organization from the James Bond films! Spectre is a package that enhances console apps. You can read about it at the following link: https://spectreconsole.net/.

Exercise 2.2 – Practice exercises

Practice exercises go deeper into the topics for this chapter.

Explore...

In this chapter, you learned how to:

• Declare variables with a specified or inferred type.
• Use some of the built-in types for numbers, text, and Booleans.
• Choose between number types.
• Control output formatting in console apps.

In the next chapter, you will learn about operators, branching, looping, converting between types, and how to handle exceptions.