• This is the order of initialization when instantiating any class:
  1. Static Fields (first time class access only: static members or first instance)
  2. Static Constructor (first time class access only: static members or first instance)
  3. Instance fields (each instance)
  4. Instance constructor (each instance)

Accessibility Options

• public: all code can access member
• private: only code within the same type can access member
• protected: code within type or subtype can access member
• internal: code within the same assembly can access member
• protected internal: code within the same assembly, within the same type, or within a subtype can access member

Allowed Levels of Accessibility

• Class: can be public or internal (default is internal) [can only be public if parent class is public]
• Namespace: always public
• Class members: can be public, private, protected, internal or protected internal (default is private)
• Struct members: can be public, private, or internal (default is private)
• Interface members: always public
• Enumeration members: always public

Constructors

• Internally, the interaction between the new operator and the constructor is as follows:
  1. The new operator retrieves memory from the memory manager and calls the specified constructor, passing the initialized memory to the constructor.
  2. Next, the remainder of the constructor chain executes, passing around the initialized memory between constructors.
  3. When execution completes on the constructor, the new operator returns the memory reference, now referring to the memory in its initialized form.
• When an exception occurs while initializing another object in a constructor, the runtime will automatically wrap the exception into a **TypeInitializationException**.

Default Constructors

• If a class has no explicitly defined constructor, then the C# compiler adds one during compilation.
  • This constructor takes no parameters and is, therefore, the default constructor by definition.
• As soon as you add an explicit constructor with parameters to a class, the C# compiler no longer provides a default constructor.
  • It is possible for programmers to define a default constructor explicitly.