C Sharp —

Access Modifiers

Now that we've noted the different types that can be defined as members of a C# class, let's look at an important modifier used to specify how visible, or accessible, a given member is to code outside its own class. These modifiers are called access modifiers and are listed in Table 5-1.

Table 5-1 C# Access Modifiers-

Access Modifier
Description
public
Signifies that the member is accessible from outside the class's definition and hierarchy of derived classes.
protected
The member is not visible outside the class and can be accessed by derived classes only.
private
The member cannot be accessed outside the scope of the defining class. Therefore, not even derived classes have access to these members.
internal
The member is visible only within the current compilation unit. The internal access modifier creates a hybrid of public and protected accessibility depending on where the code resides.

Note that unless you want a member to have the default access modifier of private, you must specify an access modifier for the member. This is in contrast to C++ where a member not explicitly decorated with an access modifier takes on the visibility characteristics of the previously stated access modifier. For example, in the following C++ code, the members a, b, and c are defined with public visibility, and the members d and e are defined as protected members: -

class CAccessModsInCpp
{
    public:
    int a;
    int b;
    int c;
    protected:
        int d;
        int e;
}

To accomplish the same goal in C#, this code would have to be changed to the following: -

class AccessModsInCSharp
{
    public int a;
    public int a;
    public int a;
    protected int d;
    protected int d;
}

The following C# code results in the member b being declared as private: -

public MoreAccessModsInCSharp
{
    public int a;
    int b;
}