Ivor Horton's Beginning Visual C++ 2012

DEFINING VARIABLES

A fundamental objective in all computer programs is to manipulate some data and get some answers. An essential element in this process is having a piece of memory that you can call your own, that you can refer to using a meaningful name, and where you can store an item of data. Each individual piece of memory so specified is called a variable.

As you already know, each variable will store a particular kind of data, and the type of data that can be stored is fixed when you define the variable in your program. One variable might store whole numbers (that is, integers), in which case, you couldn’t use it to store numbers with fractional values. The value that each variable contains at any point is determined by the statements in your program, and, of course, its value will usually change many times as the program calculation progresses.

The next section looks first at the rules for naming a variable when you introduce it into a program.

Naming Variables

The name you give to a variable is called an identifier or, more conveniently, a variable name. Variable names can include the letters A-z (upper- or lowercase), the digits 0-9, and the underscore character. No other characters are allowed, and if you happen to use some other character, you will typically get an error message when you try to compile the program. Variable names must also begin with either a letter or an underscore. Names are usually chosen to indicate the kind of information to be stored.

Because ...