More About Classes - Illustrated C# 2005 - page 99

Static Fields
Besides instance fields, classes can also have static fields .

￿ A static field is shared by all the instances of the class.

- With a static field, all the instances access the same memory location.

- If the value of the memory location is changed by one instance, the change is visible

to all the instances.

￿The static modifier is used to declare a field static, as follows:

class D
{
int Mem1; // Instance field
static int Mem2; // Static field
↑
Keyword
}

For example, the code in Figure 6-3 declares class D with static field Mem2 and instance field
Mem1 . Main defines two instances of class D .

￿Because Mem2 is static, both instances of class D share a single Mem2 field.

￿ f Mem2 is changed in one instance, it is changed in the other as well.

￿Member Mem1 is not declared static , so each instance has its own copy.

Figure 6-3. Static and non-static data members