In simple words, C# (pronounced See-Sharp) is a programming language that is developed by Microsoft. C# is approved by International Standards Organization (ISO) and European Computer Manufacturers Association (ECMA).

This is the definition on the official website (https://docs.microsoft.com/en-us/dotnet/csharp/tour-of-csharp/index):

Language C# is designed to adhere to Common Language Infrastructure (CLI), which we discussed on day one.

C# is the most popular professional language because of the following reasons:

• It is an object-oriented language
• It is component-oriented
• It is a structured language
• The main part that makes it the most popular: this is a part...

Before we start writing a program in C#, let's first go back to day one, where we discussed the various IDEs and editors that are helpful in writing programs/applications using the C# language. Revisit day one and understand various editors and IDEs and check why we should go with one of our choice. We will be using Visual Studio 2017 update 3 for all our examples in this book.

To get start with a simple C# program (we will create a console application), follow these steps:

1. Initiate your Visual Studio.
2. Go to File | New | Project (or ctrl +Shift + N).
3. Under Visual C# node, select .NET Core and then select Console App.
4. Name your program, say, Day02, and click on OK (see highlighted text in the following figure...

Reserved keywords are nothing but predefined words that have special meaning for the compilers. You cannot use these reserved keywords as normal text or identifiers unless you explicitly tell the compiler that this word is not meant to reserve for the compiler.

C# keywords are divided into the following categories:

• Types: In C#, the typing system is divided into value type, reference type, and pointer type.
• Modifiers: As is self-explanatory from its name, modifiers are used to modify the declaration of types and members of a specific type.
• Statement keywords: These are programming instructions that execute in a sequence.
• Method parameters: These can be declared as a value type or a ref type and values can be passed using out or ref keywords...

Type conversion means converting one type into another type. Alternatively, we call it as casting or type casting. Type conversion is broadly divided into the following categories.

Implicit conversion is the conversion that is performed by the C# compiler internally to match the the type of variable by assignment of values to that variable. This action happens implicitly, and there's no need to write any extra code to obey the type-safe mechanism. In implicit conversions, only smaller to larger types and derived classes to base class is possible.

In C#, you can evaluate different kinds of expression that would or would not generate the results. Whenever you say something like what would happen if result >0, in that case, we are stating something. This can be a decision-making statement, result-making statement, assignment statement, or any other activity statement. On the other hand, loops are a code block that repeatedly executes a couple of statements.

In this section, we will discuss statements and loops in detail.

A statement should perform some action before returning a result. In other words, if you are writing a statement, that statement should say something. To do that, it has to execute some inbuilt or custom operations. Statements can depend upon a decision or can be a part of the result of any existing statement. The official page (https://docs.microsoft.com/en-us/dotnet/csharp...