Working with Variables, Operators, and Expressions in Microsoft Visual C#

After completing this chapter, you will be able to:

• Understand statements, identifiers, and keywords.
• Use variables to store information.
• Work with primitive data types.
• Use arithmetic operators such as the plus sign (+) and the minus sign (–).
• Increment and decrement variables.

Chapter 1, “Welcome to C#,” presents how to use the Microsoft Visual Studio 2015 programming environment to build and run a console program and a graphical application. This chapter introduces you to the elements of Microsoft Visual C# syntax and semantics, including statements, keywords, and identifiers. You’ll study the primitive types that are built in to the C# language and the characteristics of the values that each type holds. You’ll also see how to declare and use local variables (variables that exist only in a method or other small section of code), learn about the arithmetic operators that C# provides, find out how to use operators to manipulate values, and learn how to control expressions containing two or more operators.

Understanding statements

A statement is a command that performs an action, such as calculating a value and storing the result or displaying a message to a user. You combine statements to create methods. You’ll learn more about methods in Chapter 3, “Writing methods and applying scope,” but for now, think of a method as a named sequence of statements. Main, which was introduced in the previous chapter, is an example of a method.

Statements in C# follow a well-defined set of rules describing their format and construction. These rules are collectively known as syntax. (In contrast, the specification of what statements do is collectively known as semantics.) One of the simplest and most important C# syntax rules states that you must terminate all statements with a semicolon. For example, Chapter 1 demonstrates that without the terminating semicolon, the following statement won’t compile:

Console.WriteLine("Hello, World!");

TIP

C# is a “free format” language, which means that white space, such as a space character or a new line, is not significant except as a separator. In other words, you are free to lay out your statements in any style you choose. However, you should adopt a simple, consistent layout style to make your programs easier to read and understand.

The trick to programming well in any language is to learn the syntax and semantics of the language and then use the language in a natural and idiomatic way. This approach makes your programs easier to maintain. As you progress through this book, you’ll see examples of the most important C# statements.