C# Language Specification

Variable categories

C# defines seven categories of variables: static variables, instance variables, array elements, value parameters, reference parameters, output parameters, and local variables. The sections that follow describe each of these categories.

In the example

class A
{
public static int x;
int y;

void F(int[] v, int a, ref int b, out int c) {

int i = 1;
c = a + b++;
}
}

x is a static variable, y is an instance variable, v[0] is an array element, a is a value parameter, b is a reference parameter, c is an output parameter, and i is a local variable.

1. Static variables

A field declared with the static modifier is called a static variable. A static variable comes into existence before execution of the static constructor (§10.12) for its containing type, and ceases to exist when the associated application domain ceases to exist.

The initial value of a static variable is the default value (§5.2) of the variable’s type.

For purposes of definite assignment checking, a static variable is considered initially assigned.

2.