Definition

We all know what a class is, refer the Syntax part

Syntax

Class definition syntax (in a .h file)

class Name {
	// Members can be functions (methods) or data (variables)

	public:
		// public member declarations and definitions go here

	private:
		// private member declarations and definitios go here

}; // class Name

Class member function definition syntax (in a .cc file)

// Class member function can be:
//   1) define within the class definiton
//   or 
//   2) declare within the class definition and then define elsewhere

retType Name::FunctionName(type1 param1, ..., typeN paramN) {
	// body statements
}

Class Organization

It’s a little more complex than in C when modularizing with struct definition:

• Class definition is part of interface and should go in .h file
  • Private members still must be included in definition
    • The compiler needs to know how much space to reserve for the variables
• Usually put member function definitions into companion .cc file with implementation
  • Common exception: setter and getter methods, some would prefer to put the implementation in the header file
• These files can also include non-member functions that uses the class in the header file

Unlike Java, C++ does not enforce file names, you can name files anything you want

• But normally Name.cc and Name.h for class Name

Constructors

A constructor initializes a newly instantiated object

• A class can have multiple constructors that differ in parameters
  • Which one is invoked depends on how the object is instantiated

C++ will automatically create a synthesized default constructor if you have no user-defined constructors

• Takes no arguments and calls the default constructors on all non-”plain old data” member variables
• Synthesized default constructor will fail if you have non-initialized const or reference data members.