C# 5.0 Programmer's Reference

Variable Declaration Syntax ❘ 61
Fields
A variable that is declared at the class level, outside of any method, is called a field.
Most developers recommend that you use properties instead of fields. Properties are
described in the section “Properties” later in this chapter.
The pieces of this declaration are
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attributes—One or more attributes that specify extra properties for the variable. The following
section, “Attributes,” describes attributes in more detail.
accessibility—This determines which code can access the variable. The section
“Accessibility” later in this chapter describes accessibility values in more detail.
const—If you include this, the variable is a constant and its value cannot be changed later.
Use the value to assign the constant a value.
readonly—If you include this, the variable is similar to a constant except its value can be
set either with a value clause or in the class’s constructor.
static—This keyword indicates the variable is shared by all instances of the class.
volatile—This keyword indicates the variable might be modified by code running in multiple
threads running at the same time.
type—The data type you want the variable to have.
[]—Include empty square brackets [] to make an array.
name—The name you want the variable to have.
= value—The value you want the variable to initially have.
For example, the following code defines a publically visible constant int variable named NumSquares
and initializes it to the value 8.
public const int NumSquares = 8;
The section “Static, Constant, and Volatile Variables” later in this chapter provides more detail on
the static, const, readonly, and volatile keywords.
You can define and even initialize multiple variables of the same type in a single statement. The
following statement declares and initializes two int variables.
public int value1 = 10, value2 = 20;
TIP Many developers prefer not to initialize multiple variables in the same statement
to keep the code easier to read.
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